Environment variables are accessible in UWP/WinRT apps

[sergio-nsk]

Environment variables, for example GTEST_FILTER, GTEST_OUTPUT can be set before getting WinRT app run. GoogleTest can read environment variables and use them. It's easier than setting and passing command line parameters to WinRT app.

[higher-performance]

Hi, thanks for the contribution. To clarify, have you tested that this change does what you intend?
I'm a bit confused because I see here that

This API cannot be used in applications that execute in the Windows Runtime.

which suggests to me this change shouldn't work.

[sergio-nsk]

@higher-performance Yes, of course I tested it. My first approach was using command line parameters, but this is so an extra hard task for UWP/WinRT applications, then I tried using environment variables and discovered that disabled code block, enabled it, and it worked perfectly. Honestly, I took a look at GetEnvironmentVariable() and I didn't see what could prevent getenv() from working:

Minimum supported client	Windows XP [desktop apps | UWP apps]
Minimum supported server	Windows Server 2003 [desktop apps | UWP apps]

[higher-performance]

Thanks. Yeah, I assumed it's not that getenv wouldn't work, but that getenv (unlike GetEnvironmentVariableA) wasn't declared for WinRT. But looking at the headers, I don't see that right now. I'm not familiar with UWP or WinRT personally, so I'm not sure why this macro was there in the first place, and I'd need to figure that out before I can feel comfortable approving this. Let me see if I can figure that out. Thanks for the contribution!