Minimal changes to fix build failures on Microsoft Visual Studio 2015

[dankegel]

Should fix #1033

Fixes the following errors:

hash_map(17): error C2338: <hash_map> is deprecated and will be REMOVED. Please use <unordered_map>. You can define _SILENCE_STDEXT_HASH_DEPRECATION_WARNINGS to acknowledge that you have received this warning. [googlemock\gtest\gtest-printers_test.vcxproj]
hash_set(17): error C2338: <hash_set> is deprecated and will be REMOVED. Please use <unordered_set>. You can define _SILENCE_STDEXT_HASH_DEPRECATION_WARNINGS to acknowledge that you have received this warning. [googlemock\gtest\gtest-printers_test.vcxproj]
googletest\test\gtest_catch_exceptions_test_.cc(152): error C2220: warning treated as error - no 'object' file generated
googletest\test\gtest_catch_exceptions_test_.cc(152): warning C4297: 'CxxExceptionInDestructorTest::~CxxExceptionInDestructorTest': function assumed not to throw an exception but does
  googletest\test\gtest_catch_exceptions_test_.cc(152): note: destructor or deallocator has a (possibly implicit) non-throwing exception specification

There were already some checks for _MSC_VER in the code, so this commit
continues in that vein.

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[googlebot]

CLAs look good, thanks!

[ghost]

When is this going to be implemented?

[MrSapps]

Is there some reason not to merge this? AppVeyor build has been broken for a LONG time.

[BillyDonahue]

Sorry for the delay.

[dankegel]

Thanks!