Don't force inlining for msvc targets.

Don't force inlining for msvc targets.

INLINE is defined as __forceinline for vs* configs, but is the
normal, compiler-discretion inline for gcc/clang configs. This
makes many functions very large when building for windows targets,
much larger than they are elsewhere.

Use '__inline' as a consistent definition to get consistent function
sizes. Although Visual Studio documentation says that 'inline' is
only available in C+ code. This is probably incorrect, since Visual
Studio 2017 accepts C99 'inline' even when passed /TC. Nevertheless,
this commit uses the recommended '__inline' for consistency.

Thanks to David Major for the diagnosis.

Change-Id: Ib0b31a3afcea77822c84fe3c6cd452add66d825a