Add time.h for Windows build.
Check for the right function pointer

This code checked whether one function pointer was non-null,
but the went on to call a different function pointer. Check
for the one that actually was called.
Fix the indentation of some nasm macros
Merge pull request #500 from mstorsjo/fix-func-ptr-check

Check for the right function pointer
Merge pull request #499 from ethanhugg/winbuild_time

Add time.h for Windows build.
Merge pull request #502 from mstorsjo/fix-macro-indentation

Fix the indentation of some nasm macros