Remove mingw-std-threads from 3rd party deps and use native libs/headers instead (#7283)

* Remove mingw-std-threads from 3rd party deps

 and use native libs/headers instead

* switch MinGW to POSIX in CI

plugins/VstBase/RemoteVstPlugin.cpp

@@ -87,11 +87,7 @@
 #undef Unsorted
 #endif
 
-#ifdef USE_MINGW_THREADS_REPLACEMENT
-#	include <mingw.mutex.h>
-#else
-#	include <mutex>
-#endif
+#include <mutex>
 
 #include <algorithm>
 #include <vector>

plugins/VstBase/RemoteVstPlugin/CMakeLists.txt

@@ -66,21 +66,6 @@ endif()
 
 if(IS_MINGW)
 	SET(CMAKE_REQUIRED_FLAGS "-std=c++17")
-
-	CHECK_CXX_SOURCE_COMPILES("
-	#include <mutex>
-	int main(int argc, const char* argv[]) {
-		std::mutex m;
-		return 0;
-	}
-	" HAS_STD_MUTEX)
-
-	if(NOT HAS_STD_MUTEX)
-		target_include_directories(${EXE_NAME} SYSTEM PRIVATE
-			"${LMMS_SOURCE_DIR}/src/3rdparty/mingw-std-threads")
-		target_compile_definitions(${EXE_NAME} PRIVATE
-			-DUSE_MINGW_THREADS_REPLACEMENT)
-	endif()
 endif()
 
 if(LMMS_BUILD_WIN32)

plugins/ZynAddSubFx/CMakeLists.txt

@@ -111,12 +111,6 @@ set_target_properties(zynaddsubfx_nio PROPERTIES SYSTEM TRUE)
 set_target_properties(zynaddsubfx_gui PROPERTIES SYSTEM TRUE)
 set_target_properties(zynaddsubfx_synth PROPERTIES SYSTEM TRUE)
 
-if(MINGW)
-	target_link_libraries(zynaddsubfx_nio PUBLIC mingw_stdthreads)
-	target_link_libraries(zynaddsubfx_gui PUBLIC mingw_stdthreads)
-	target_link_libraries(zynaddsubfx_synth PUBLIC mingw_stdthreads)
-endif()
-
 # Relative include paths don't work automatically for the GUI, because the
 # generated C++ files aren't in the source directory. Thus, add the expected
 # source directory as an additional include directory.

plugins/ZynAddSubFx/ThreadShims.h

@@ -1,9 +1,3 @@
 #include <condition_variable>
 #include <mutex>
 #include <thread>
-
-#if defined(__MINGW32__) && !defined(_GLIBCXX_HAS_GTHREADS)
-#	include <mingw.condition_variable.h>
-#	include <mingw.mutex.h>
-#	include <mingw.thread.h>
-#endif