Prevent overriding of user-defined CFLAGS.


--- a/media_driver/cmake/linux/media_compile_flags_linux.cmake
+++ b/media_driver/cmake/linux/media_compile_flags_linux.cmake
@@ -51,16 +51,26 @@ set(MEDIA_COMPILER_FLAGS_COMMON
     -fdata-sections
     -ffunction-sections
     -Wl,--gc-sections
+)
 
+if (OVERRIDE_COMPILER_FLAGS)
+    list (APPEND MEDIA_COMPILER_FLAGS_COMMON
     # -m32 or -m64
     -m${ARCH}
+)
+endif(OVERRIDE_COMPILER_FLAGS)
 
+list (APPEND MEDIA_COMPILER_FLAGS_COMMON
     # Global defines
     -DLINUX=1
     -DLINUX
     -DNO_RTTI
     -DNO_EXCEPTION_HANDLING
     -DINTEL_NOT_PUBLIC
+)
+
+if (OVERRIDE_COMPILER_FLAGS)
+    list (APPEND MEDIA_COMPILER_FLAGS_COMMON
     -g
 )
 
@@ -73,6 +83,7 @@ if(${UFO_MARCH} STREQUAL "slm")
         -mtune=atom
     )
 endif()
+endif(OVERRIDE_COMPILER_FLAGS)
 
 if(${ARCH} STREQUAL "64")
     set(MEDIA_COMPILER_FLAGS_COMMON
@@ -189,9 +200,11 @@ include(${MEDIA_EXT_CMAKE}/ext/linux/media_compile_flags_linux_ext.cmake OPTIONA
 if(${PLATFORM} STREQUAL "linux")
     #set predefined compiler flags set
     add_compile_options("${MEDIA_COMPILER_FLAGS_COMMON}")
+if (OVERRIDE_COMPILER_FLAGS)
     add_compile_options("$<$<CONFIG:Debug>:${MEDIA_COMPILER_FLAGS_DEBUG}>")
     add_compile_options("$<$<CONFIG:Release>:${MEDIA_COMPILER_FLAGS_RELEASE}>")
     add_compile_options("$<$<CONFIG:ReleaseInternal>:${MEDIA_COMPILER_FLAGS_RELEASEINTERNAL}>")
+endif(OVERRIDE_COMPILER_FLAGS)
 
     foreach (flag ${MEDIA_COMPILER_CXX_FLAGS_COMMON})
         SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${flag}")