build: linux mingw cross-compile fixes (partial)

Enables the Linux -> win-x64 MinGW cross-compile path that got broken
after recent merges. Still INCOMPLETE — build fails later at missing
DirectX IME headers (DIMM.h) and likely more vendor SDK compat issues.
Commit captures the mechanical fixes so Jakub can adopt/iterate.

Changes:

1. toolchains/linux-mingw64.cmake — MinGW cross-compile toolchain
   (Windows x86_64 target, mingw-w64 gcc/g++/windres, lld linker).

2. CMakeLists.txt:
   - MSVC-only flags (/MP, /Zi, /DEBUG linker flag) gated behind
     if(MSVC) — they break MinGW gcc which treats /MP as filename.
   - UNICODE / _UNICODE defined globally (was inside if(MSVC), but
     WIN32_FIND_DATA etc. need it everywhere).
   - __int64 -> long long compile definition for non-MSVC compilers
     so the Granny SDK header parses.
   - -mssse3 compile option for non-MSVC so _mm_shuffle_epi8 in
     EterLib/GrpImageTexture.cpp inlines correctly.

3. Include fixes for Linux case-sensitive filesystem and stricter
   GCC standard library:
   - Poly/StdAfx.h: backslash in include path -> forward slash.
   - EterBase/Stl.h: <SSTREAM> -> <sstream>.
   - EterBase/Utils.h: add <cmath> so cos() in templates resolves.
   - AudioLib/MaSoundInstance.h: add <cstdint> so uint8_t vector
     template argument is valid.
   - AudioLib/Type.h: add <cstdint> for uint32_t.
   - extern/include/utf8.h: add <cstdint> for uint8_t/uint16_t.
   - EffectLib/Type.h: typedef typename std::vector<...>::iterator
     (dependent-name C++11+ compliance).

Not committed (needs manual recreation per checkout, or git-tracking
them needs buy-in):
   - 60+ stdafx case-variant symlinks (stdafx.h, StdAfx.h, Stdafx.h)
   - 7 directory case symlinks (Eterlib, eterLib, eterBase, Gamelib,
     gamelib, Eterbase, eterbase)
   - header case-variant symlinks in individual dirs

Still failing at:
   - src/EterLib/IME.h:7 wanting DIMM.h (DirectX IME, not in extern/
     and not shipped with mingw-w64). Needs either a shim header, a
     #ifdef _MSC_VER guard, or vendoring the Microsoft DirectX IME SDK.

Work done over ~2h trying to get a fresh release cycle through from
Linux. Stopping here because each fix exposes another vendor/compat
issue that benefits from Jakub's context of the build history.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CMakeLists.txt

@@ -20,12 +20,30 @@ set(CMAKE_MSVC_DEBUG_INFORMATION_FORMAT "$<$<CONFIG:Debug,RelWithDebInfo,Release
 
 set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
-set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} /Zi")
+add_compile_definitions(UNICODE _UNICODE)
-set(CMAKE_EXE_LINKER_FLAGS_RELEASE "${CMAKE_EXE_LINKER_FLAGS_RELEASE} /DEBUG")
+add_compile_definitions("$<$<NOT:$<CXX_COMPILER_ID:MSVC>>:__int64=long long>")
+add_compile_options("$<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-mssse3>")
+if(MSVC)
+  set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} /Zi")
+endif()
+add_compile_definitions(UNICODE _UNICODE)
+add_compile_definitions("$<$<NOT:$<CXX_COMPILER_ID:MSVC>>:__int64=long long>")
+add_compile_options("$<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-mssse3>")
+if(MSVC)
+  set(CMAKE_EXE_LINKER_FLAGS_RELEASE "${CMAKE_EXE_LINKER_FLAGS_RELEASE} /DEBUG")
+endif()
 
 add_compile_options("$<$<CXX_COMPILER_ID:MSVC>:/utf-8>")
-add_compile_options(/MP)
+add_compile_definitions(UNICODE _UNICODE)
+add_compile_definitions("$<$<NOT:$<CXX_COMPILER_ID:MSVC>>:__int64=long long>")
+add_compile_options("$<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-mssse3>")
+if(MSVC)
+  add_compile_options(/MP)
+endif()
 
+add_compile_definitions(UNICODE _UNICODE)
+add_compile_definitions("$<$<NOT:$<CXX_COMPILER_ID:MSVC>>:__int64=long long>")
+add_compile_options("$<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-mssse3>")
 if(MSVC)
 	add_compile_definitions(UNICODE _UNICODE)
 endif()

extern/include/utf8.h

@@ -1,3 +1,4 @@
+#include <cstdint>
 #pragma once
 #include <string>
 #include <cstring>

src/AudioLib/MaSoundInstance.h

@@ -1,3 +1,4 @@
+#include <cstdint>
 #pragma once
 #define MA_NO_WASAPI
 #define MA_ENABLE_DSOUND

src/AudioLib/Type.h

@@ -1,3 +1,4 @@
+#include <cstdint>
 #pragma once
 
 #include <vector>

src/EffectLib/Type.h

@@ -217,7 +217,7 @@ extern BOOL GetTokenTimeEventFloat(CTextFileLoader & rTextFileLoader, const char
 template <typename T>
 void InsertItemTimeEvent(std::vector<CTimeEvent<T> >* pTable, float fTime, T fValue)
 {
-	typedef std::vector<CTimeEvent<T> >::iterator iterator;
+	typedef typename std::vector<CTimeEvent<T> >::iterator iterator;
 
 	iterator itor = std::lower_bound(pTable->begin(), pTable->end(), fTime);
 

src/EterBase/Poly/StdAfx.h

@@ -1,2 +1,2 @@
 #pragma once
-#include "..\StdAfx.h"
+#include "../StdAfx.h"

src/EterBase/Stl.h

@@ -20,7 +20,7 @@
 #include <map>
 #include <queue>
 #include <functional>
-#include <SSTREAM>
+#include <sstream>
 
 #pragma warning ( pop )
 

src/EterBase/Utils.h

@@ -1,3 +1,4 @@
+#include <cmath>
 #ifndef __INC_ETER2_ETERBASE_UTILS_H__
 #define __INC_ETER2_ETERBASE_UTILS_H__
 

toolchains/linux-mingw64.cmake

@@ -0,0 +1,17 @@
+# Cross-compile for Windows x86_64 from Linux using MinGW + LLD.
+set(CMAKE_SYSTEM_NAME Windows)
+set(CMAKE_SYSTEM_PROCESSOR x86_64)
+
+set(CMAKE_C_COMPILER   x86_64-w64-mingw32-gcc)
+set(CMAKE_CXX_COMPILER x86_64-w64-mingw32-g++)
+set(CMAKE_RC_COMPILER  x86_64-w64-mingw32-windres)
+
+set(CMAKE_FIND_ROOT_PATH /usr/x86_64-w64-mingw32)
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+set(CMAKE_EXE_LINKER_FLAGS_INIT    "-fuse-ld=lld")
+set(CMAKE_SHARED_LINKER_FLAGS_INIT "-fuse-ld=lld")
+set(CMAKE_MODULE_LINKER_FLAGS_INIT "-fuse-ld=lld")