Use -ffunction-sections/-fdata-sections/--gc-sections with clang too

This saves about 1500 kB on a production build on ARMv7.

Author: blino

Source/cmake/OptionsWPE.cmake

@@ -475,8 +475,11 @@ include(BubblewrapSandboxChecks)
 include(GStreamerChecks)
 
 # Optimize binary size for release builds by removing dead sections on unix/gcc.
-if (CMAKE_COMPILER_IS_GNUCC AND UNIX AND NOT APPLE)
-    set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -ffunction-sections -fdata-sections")
-    set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -ffunction-sections -fdata-sections -fno-rtti")
+if (COMPILER_IS_GCC_OR_CLANG AND UNIX AND NOT APPLE)
+    if (CMAKE_COMPILER_IS_GNUCC)
+        set(CMAKE_COMPILER_SIZE_OPT_FLAGS " -finline-limit=90 -fsection-anchors")
+    endif ()
+    set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE}${CMAKE_COMPILER_SIZE_OPT_FLAGS} -ffunction-sections -fdata-sections")
+    set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE}${CMAKE_COMPILER_SIZE_OPT_FLAGS} -ffunction-sections -fdata-sections -fno-rtti")
     set(CMAKE_SHARED_LINKER_FLAGS_RELEASE "${CMAKE_SHARED_LINKER_FLAGS_RELEASE} -Wl,--gc-sections")
 endif ()