GMake generated gtest_main VS 2012 project does not support variadic templates

[stevehickman]

Need to add the following preprocessor define: _VARIADIC_MAX=10

See http://stackoverflow.com/questions/8274588/c2977-stdtuple-too-many-template-arguments-msvc11

for details.

[stevehickman]

Need the same thing for the gtest and test_api VS2012 projects

[alanxz]

Yay MSVC... I'll look into what's necessary here.