libobs: Silence clang warnings for empty prototypes without void

clang expects an empty prototype to explicitly use `void`.

Also silences the warning in `libobs-opengl`, `obsglad`, `caption`,
`mac-syphon` and `obs-x264-test`.

deps/glad/CMakeLists.txt

@@ -17,6 +17,8 @@ target_link_libraries(obsglad PUBLIC OpenGL::GL)
 
 if(OS_WINDOWS)
   target_sources(obsglad PRIVATE src/glad_wgl.c include/glad/glad_wgl.h)
+elseif(OS_MACOS)
+  target_compile_options(obsglad PRIVATE -Wno-strict-prototypes)
 elseif(OS_LINUX OR OS_FREEBSD)
   if(TARGET OpenGL::EGL)
     target_sources(obsglad PRIVATE src/glad_egl.c include/EGL/eglplatform.h include/glad/glad_egl.h)

deps/libcaption/CMakeLists.txt

@@ -25,7 +25,9 @@ target_sources(
 
 target_compile_definitions(caption PRIVATE __STDC_CONSTANT_MACROS $<$<CXX_COMPILER_ID:MSVC>:_CRT_SECURE_NO_WARNINGS>)
 
-target_compile_options(caption PRIVATE $<$<CXX_COMPILER_ID:Clang,AppleClang,GNU>:-Wno-unused-but-set-parameter>)
+target_compile_options(
+  caption
+  PRIVATE "$<$<CXX_COMPILER_ID:Clang,AppleClang,GNU>:-Wno-unused-but-set-parameter;-Wno-comma;-Wno-strict-prototypes>")
 
 target_include_directories(
   caption

libobs-opengl/CMakeLists.txt

@@ -38,6 +38,7 @@ elseif(OS_MACOS)
 
   target_sources(libobs-opengl PRIVATE gl-cocoa.m)
   target_compile_definitions(libobs-opengl PRIVATE GL_SILENCE_DEPRECATION)
+  target_compile_options(libobs-opengl PRIVATE -Wno-strict-prototypes)
 
   target_link_libraries(libobs-opengl PRIVATE ${COCOA} ${IOSURF})
 elseif(OS_LINUX OR OS_FREEBSD)

libobs/cmake/os-macos.cmake

@@ -39,5 +39,7 @@ target_sources(
           util/threading-posix.h
           util/apple/cfstring-utils.h)
 
+target_compile_options(libobs PUBLIC -Wno-strict-prototypes)
+
 set_property(SOURCE util/platform-cocoa.m obs-cocoa.m PROPERTY COMPILE_FLAGS -fobjc-arc)
 set_property(TARGET libobs PROPERTY FRAMEWORK TRUE)

plugins/obs-x264/cmake/x264-test.cmake

@@ -6,3 +6,7 @@ target_link_libraries(obs-x264-test PRIVATE OBS::opts-parser)
 add_test(NAME obs-x264-test COMMAND obs-x264-test)
 
 set_target_properties(obs-x264-test PROPERTIES FOLDER plugins/obs-x264)
+
+if(OS_MACOS)
+  target_compile_options(obs-x264-test PRIVATE -Wno-strict-prototypes)
+endif()