Make Xcode use GCC to build LÖVE instead of Clang, to avoid some annoying linker error.

platform/macosx/love.xcodeproj/project.pbxproj

@@ -1966,7 +1966,7 @@
 				GCC_OPTIMIZATION_LEVEL = 0;
 				GCC_TREAT_IMPLICIT_FUNCTION_DECLARATIONS_AS_ERRORS = NO;
 				GCC_TREAT_NONCONFORMANT_CODE_ERRORS_AS_WARNINGS = NO;
-				GCC_VERSION = com.apple.compilers.llvm.clang.1_0;
+				GCC_VERSION = com.apple.compilers.llvmgcc42;
 				GCC_WARN_64_TO_32_BIT_CONVERSION = NO;
 				GCC_WARN_ABOUT_MISSING_NEWLINE = NO;
 				GCC_WARN_ABOUT_MISSING_PROTOTYPES = NO;
@@ -2018,7 +2018,7 @@
 				GCC_INPUT_FILETYPE = automatic;
 				GCC_TREAT_IMPLICIT_FUNCTION_DECLARATIONS_AS_ERRORS = NO;
 				GCC_TREAT_NONCONFORMANT_CODE_ERRORS_AS_WARNINGS = NO;
-				GCC_VERSION = com.apple.compilers.llvm.clang.1_0;
+				GCC_VERSION = com.apple.compilers.llvmgcc42;
 				GCC_WARN_64_TO_32_BIT_CONVERSION = NO;
 				GCC_WARN_ABOUT_MISSING_NEWLINE = NO;
 				GCC_WARN_ABOUT_MISSING_PROTOTYPES = NO;