headers: Fix ftime function for __CRT__NO_INLINE

When __CRT__NO_INLINE is enabled then ftime function ignored the
_USE_32BIT_TIME_T settings.

Fix this problem by declaring ftime function with __MINGW_ASM_CALL
attribute with correct alias based on _USE_32BIT_TIME_T settings.

With this change the inline variant of ftime function is not needed
anymore as it was just wrapper around aliased function, which is now
correctly resolved via __MINGW_ASM_CALL.

Signed-off-by: Martin Storsjö <martin@martin.st>