Fix Debug.xcconfig

Lib/Configurations/Debug.xcconfig

@@ -6,6 +6,6 @@ COPY_PHASE_STRIP = NO;
 ENABLE_TESTABILITY = YES;
 GCC_OPTIMIZATION_LEVEL = 0;
 ONLY_ACTIVE_ARCH = YES;
-SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+SWIFT_OPTIMIZATION_LEVEL = -Onone;
 
 GCC_PREPROCESSOR_DEFINITIONS = $(inherited) DEBUG=1;