We should use -Os(fastest smallest) for Release builds to reduce code size

VLC.xcodeproj/project.pbxproj

@@ -4470,6 +4470,7 @@
 				ENABLE_TESTABILITY = YES;
 				GCC_C_LANGUAGE_STANDARD = gnu99;
 				GCC_DYNAMIC_NO_PIC = NO;
+				GCC_OPTIMIZATION_LEVEL = 0;
 				GCC_PREPROCESSOR_DEFINITIONS = (
 					"DEBUG=1",
 					"$(inherited)",
@@ -4590,7 +4591,6 @@
 				EXCLUDED_SOURCE_FILE_NAMES = "";
 				GCC_C_LANGUAGE_STANDARD = gnu11;
 				GCC_ENABLE_CPP_EXCEPTIONS = NO;
-				GCC_OPTIMIZATION_LEVEL = 0;
 				GCC_PRECOMPILE_PREFIX_HEADER = YES;
 				GCC_PREFIX_HEADER = "Sources/VLC for iOS-Prefix.pch";
 				INFOPLIST_FILE = "Sources/VLC for iOS-Info.plist";
@@ -4608,7 +4608,7 @@
 				"PROVISIONING_PROFILE[sdk=iphoneos*]" = "";
 				SKIP_INSTALL = NO;
 				SWIFT_OBJC_BRIDGING_HEADER = "VLC-iOS-Bridging-Header.h";
-				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_OPTIMIZATION_LEVEL = "-O";
 				SWIFT_VERSION = 3.0;
 				VALID_ARCHS = "arm64 armv7 armv7s";
 			};
@@ -4800,7 +4800,6 @@
 				EXCLUDED_SOURCE_FILE_NAMES = "iTunesArtwork*";
 				GCC_C_LANGUAGE_STANDARD = gnu11;
 				GCC_ENABLE_CPP_EXCEPTIONS = NO;
-				GCC_OPTIMIZATION_LEVEL = 3;
 				GCC_PRECOMPILE_PREFIX_HEADER = YES;
 				GCC_PREFIX_HEADER = "Sources/VLC for iOS-Prefix.pch";
 				INFOPLIST_FILE = "Sources/VLC for iOS-Info.plist";