Build JDK 10 on OSX 10.12 and above

https://bugs.openjdk.java.net/browse/JDK-8182299 enabled previously disabled clang warnings and was intended to also enable builds on OSX 10 + Xcode 8. Due to a mixup, this code

  #if defined(MAC_OS_X_VERSION_10_12) && \
     MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_12 && \
     __LP64__
     / 10.12 changed `mask` to NSEventMask (unsigned long long) for x86_64 builds.
  - (NSEvent *)nextEventMatchingMask:(NSEventMask)mask
  #else
  - (NSEvent *)nextEventMatchingMask:(NSUInteger)mask
  #endif
  untilDate:(NSDate *)expiration inMode:(NSString *)mode dequeue:(BOOL)deqFlag {

in jdk/src/java.desktop/macosx/native/libosxapp/NSApplicationAWT.m fails to compile starting with OSX 10.12 due to MAC_OSX_VERSION_MAX_ALLOWED being defined on the compile command line to be 10.7. A suggested fix is to remove that definition, since it places an artificial upper bound on the OSX version under which the JDK can be built. A source code search reveals no uses other than in NSApplicationAWT.m and hotspot/src/os_cpu/bsd_x86/vm/os_bsd_x86.cpp. The latter won't be affected by this change, since it checks for a version > 10.5, which is already the case.