CMakeLists.txt: conditionally use -Wpedantic

-Wpedantic is only provided by gcc >= 4.8. Since showing pedantic
warnings is not really mandatory, let's only use this option when the
compiler supports it.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

CMakeLists.txt

@@ -4,13 +4,18 @@ include(CheckLibraryExists)
 include(CheckIncludeFiles)
 include(CheckCSourceCompiles)
 include(CMakePushCheckState)
+include(CheckCCompilerFlag)
 
 if(MSVC)
 set(LIBM "")
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W4")
 else(MSVC)
 set(LIBM "m")
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC -std=c99 -Wpedantic -Wall")
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC -std=c99 -Wall")
+check_c_compiler_flag(-Wpedantic COMPILER_SUPPORTS_WPEDANTIC)
+if(COMPILER_SUPPORTS_WPEDANTIC)
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wpedantic")
+endif()
 if(CMAKE_BUILD_TYPE STREQUAL "Debug")
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -g3 -O0 -fsanitize=address")
     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,-no_pie,")