Change how OpenMPT is linked.

This is necessitated by OpenMPT being a C++ library.

Related: #1598

addons/acodec/CMakeLists.txt

@@ -458,6 +458,10 @@ add_our_addon_library(allegro_acodec
     "${AUDIO_LINK_WITH};${ACODEC_LIBRARIES}"
     )
 
+if(SUPPORT_OPENMPT AND SHARED AND NOT WANT_MONOLITH)
+    set_target_properties(allegro_acodec PROPERTIES LINKER_LANGUAGE CXX)
+endif()
+
 install_our_headers(${ACODEC_INCLUDE_FILES})
 
 add_addon(acodec)

cmake/Common.cmake

@@ -110,7 +110,7 @@ function(add_our_library target framework_name sources extra_flags link_with)
         if(WANT_STATIC_RUNTIME)
             # TODO: The -static is a bit of a hack for MSYS2 to force the static linking of pthreads.
             # There has to be a better way.
-            set(extra_link_flags "-static-libgcc -static-libstdc++ -static -lpthread")
+            set(extra_link_flags "-static-libgcc -static-libstdc++ -static -lpthread -Wl,--exclude-libs=libpthread.a -Wl,--exclude-libs=libgcc_eh.a")
         endif()
     endif()
 
@@ -121,7 +121,7 @@ function(add_our_library target framework_name sources extra_flags link_with)
     if(NOT BUILD_SHARED_LIBS)
         set(static_flag "-DALLEGRO_STATICLINK")
     endif(NOT BUILD_SHARED_LIBS)
-    
+
     if(NOT ANDROID)
         set_target_properties(${target}
             PROPERTIES
@@ -137,7 +137,7 @@ function(add_our_library target framework_name sources extra_flags link_with)
             )
         set_property(GLOBAL APPEND PROPERTY JNI_LIBS ${target})
     endif(NOT ANDROID)
-    
+
     # Construct the output name.
     set(output_name ${target})
     append_lib_type_suffix(output_name)
@@ -261,12 +261,12 @@ function(fix_executable nm)
 
         # FIXME:We want those as project attributes, not target attributes, but I don't know how
         set_target_properties(${nm} PROPERTIES XCODE_ATTRIBUTE_CODE_SIGN_IDENTITY "iPhone Developer")
-        
+
         # We have to add an icon to every executable on IPhone else
         # cmake won't create a resource copy build phase for us.
         # And re-creating those by hand would be a major pain.
         set_target_properties(${nm} PROPERTIES MACOSX_BUNDLE_ICON_FILE icon.png)
-        
+
         set_source_files_properties("${CMAKE_SOURCE_DIR}/misc/icon.png" PROPERTIES
             MACOSX_PACKAGE_LOCATION "Resources"
         )
@@ -293,7 +293,7 @@ function(add_our_executable nm)
     if(NOT OPTS_SRCS)
         set(OPTS_SRCS "${nm}.c")
     endif()
-    
+
     if(IPHONE)
         set(EXECUTABLE_TYPE MACOSX_BUNDLE)
         set(OPTS_SRCS ${OPTS_SRCS} "${CMAKE_SOURCE_DIR}/misc/icon.png")
@@ -307,7 +307,7 @@ function(add_our_executable nm)
     if(NOT BUILD_SHARED_LIBS)
         list(APPEND OPTS_DEFINES ALLEGRO_STATICLINK)
     endif()
-    
+
     foreach(d ${OPTS_DEFINES})
         set_property(TARGET ${nm} APPEND PROPERTY COMPILE_DEFINITIONS ${d})
     endforeach()
@@ -337,7 +337,7 @@ function(add_our_executable nm)
             set_target_properties(${nm} PROPERTIES LINK_FLAGS "-Wl,-subsystem,windows")
         endif()
     endif()
-   
+
     fix_executable(${nm})
 endfunction()