CMake: don't add -pthread for Windows builds

It can generate some warnings or compilations errors.

The official CMake way of picking the thread library [^1] should probably be used for non-Windows targets.

[^1]: https://cmake.org/cmake/help/latest/module/FindThreads.html

Signed-off-by: Steve Lhomme <robux4@ycbcr.xyz>

Author: robUx4

CMakeLists.txt

@@ -121,8 +121,11 @@ elseif(UNIX OR MINGW)
         set(OPT_DBG "-DNDEBUG") # disable assert
     endif()
 
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OPT_DBG} -${OPT_LV} -fomit-frame-pointer -pthread")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OPT_DBG} -${OPT_LV} -fomit-frame-pointer")
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wno-unused-function -Wno-pointer-sign -Wno-pointer-to-int-cast")
+    if(NOT WIN32)
+      set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -pthread")
+    endif()
     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -lm")
 else()
     message("Unknown compiler")

src/CMakeLists.txt

@@ -182,6 +182,9 @@ if(NOT MSVC)
         set(EXTRA_CFLAGS "-DOAPV_STATIC_DEFINE")
         set(EXTRA_CFLAGS_PRIVATE "")
     endif()
+    if(NOT WIN32)
+        set(EXTRA_CFLAGS_PRIVATE "${EXTRA_CFLAGS_PRIVATE} -pthread")
+    endif()
     configure_file(
       "${CMAKE_SOURCE_DIR}/pkgconfig/${LIB_NAME_BASE}.pc.in"
       "${CMAKE_BINARY_DIR}/${LIB_NAME_BASE}.pc" @ONLY)