Specify when iOS got headers for MetalPerformanceShaders. (#4524)

Fixes this problem in the MT4134 test:

    Process exited with code 1, command:
    /Applications/Xcode83.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang  -Wno-receiver-forward-class -Wno-objc-missing-super-calls -gdwarf-2 -I/Users/builder/jenkins/workspace/xamarin-macios/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/SDKs/MonoTouch.iphonesimulator.sdk/usr/include -isysroot /Applications/Xcode83.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator10.3.sdk -Qunused-arguments -fobjc-legacy-dispatch -fobjc-abi-version=2 -mios-simulator-version-min=11.4 -arch x86_64 -c -o /Users/builder/jenkins/workspace/xamarin-macios/xamarin-macios/tests/mtouch/bin/Debug/tmp-test-dir/Xamarin.Tests.BundlerTool.CreateTemporaryDirectory513/mtouch-test-cache/x86_64/registrar.o -x objective-c++ /Users/builder/jenkins/workspace/xamarin-macios/xamarin-macios/tests/mtouch/bin/Debug/tmp-test-dir/Xamarin.Tests.BundlerTool.CreateTemporaryDirectory513/mtouch-test-cache/registrar.m
    In file included from /Users/builder/jenkins/workspace/xamarin-macios/xamarin-macios/tests/mtouch/bin/Debug/tmp-test-dir/Xamarin.Tests.BundlerTool.CreateTemporaryDirectory513/mtouch-test-cache/registrar.m:2:
    /Users/builder/jenkins/workspace/xamarin-macios/xamarin-macios/tests/mtouch/bin/Debug/tmp-test-dir/Xamarin.Tests.BundlerTool.CreateTemporaryDirectory513/mtouch-test-cache/registrar.h:47:9: fatal error: 'MetalPerformanceShaders/MetalPerformanceShaders.h' file not found
    #import <MetalPerformanceShaders/MetalPerformanceShaders.h>

Note that the error is because the test is building with Xcode 8.3 (and this
is also why the problem wasn't found by the PR bots: they don't have older
Xcodes installed to run this particular test).

tools/common/Frameworks.cs

@@ -256,7 +256,7 @@ public class Frameworks : Dictionary <string, Framework>
 				{ "WatchConnectivity", "WatchConnectivity", 9 },
 				{ "ModelIO", "ModelIO", 9 },
 				{ "MetalKit", "MetalKit", 9 },
-				{ "MetalPerformanceShaders", "MetalPerformanceShaders", 9 },
+				{ "MetalPerformanceShaders", "MetalPerformanceShaders", new Version (9, 0), new Version (11, 0) /* MPS got simulator headers in Xcode 9 */ },
 				{ "GameplayKit", "GameplayKit", 9 },
 				{ "HealthKitUI", "HealthKitUI", 9,3 },