Merge pull request #3333 from PrismLauncher/backport-3330-to-release-9.x

[Backport release-9.x] Use better compile flags for MINGW

CMakeLists.txt

@@ -78,6 +78,13 @@ else()
     # ATL's pack list needs more than the default 1 Mib stack on windows
     if(WIN32)
         set(CMAKE_EXE_LINKER_FLAGS "-Wl,--stack,8388608 ${CMAKE_EXE_LINKER_FLAGS}")
+
+        # -ffunction-sections and -fdata-sections help reduce binary size
+        # -mguard=cf enables Control Flow Guard
+        # TODO: Look into -gc-sections to further reduce binary size
+        foreach(lang C CXX)
+            set("CMAKE_${lang}_FLAGS_RELEASE" "-ffunction-sections -fdata-sections -mguard=cf")
+        endforeach()
     endif()
 endif()