Define GOOGLE_ATTRIBUTE_NOINLINE for MSVC. Workaround for VS2015 Release build compiler bug.

See issue #240 - MSVC in VS2015 seems to inline a function it shouldn't. My original workaround was to disable inlining for the whole file, but I found a way to do it on just this specific function using __declspec(noinline).
Unfortunately __declspec has to go at the start of the function declaration, while __attribute in GCC can go either before or after. I had to move lots of GOOGLE_ATTRIBUTE_NOLINE to make it compile. I have not yet tested this change with GCC.

Will there be other side effects of defining this, given it wasn't previously?

I also noticed a few functions marked with both the 'inline' keyword, and GOOGLE_ATTRIBUTE_NOINLINE - huh? Is there an explanation for this, or is it an oversight?