Mac: enabled link-time optimization for Release builds of love

platform/macosx/love-framework.xcodeproj/project.pbxproj

@@ -2364,6 +2364,7 @@
 				);
 				LD_RUNPATH_SEARCH_PATHS = "@rpath";
 				LIBRARY_SEARCH_PATHS = "";
+				LLVM_LTO = YES;
 				MACOSX_DEPLOYMENT_TARGET = 10.6;
 				ONLY_ACTIVE_ARCH = NO;
 				USE_HEADERMAP = NO;