Fix extern_inline for MSVC and clang-cl

Prior to this change, no inline function bodies would be provided for
MSVC. This change fixes that, so nasm will be slightly faster.

With clang-cl, however, there would be LNK4006 warnings if the compiler
chooses not to inline the ilog2 functions. The easiest way to observe
this is with `nmake /f Mkfiles/msvc.mak CC=clang-cl DEBUG=1`. This
disables inlining, and I see this at the end of the link:
  ilog2.obj : warning LNK4006: ilog2_32 already defined in outmacho.obj; second definition ignored
  ilog2.obj : warning LNK4006: ilog2_64 already defined in eval.obj; second definition ignored
  ilog2.obj : warning LNK4006: alignlog2_32 already defined in outmacho.obj; second definition ignored

When additional instrumentation (-fprofile-instr-generate) is enabled,
the warning can become an error, as we discovered in
https://crbug.com/989745.

MSVC and compilers pretending to be MSVC (clang-cl) implement inline in
C with C++ semantics. In C++, inline functions are emitted by the
compiler whenever they are needed and the linker discards duplicate
inline function definitions. This change adds a new HAVE_MSVC_INLINE
macro and adjusts the ifdefs to handle this mode. I chose to keep
ilog2.c as part of the build, and to have it emit duplicate definitions
of all the inline functions. An alternative solution would be to exclude
it from the build, but I felt it was best to solve this in source code
instead of the build system.

R=dalecurtis@chromium.org, davidben@chromium.org

Chromium-specific: I reran find_patches.py with some modifications to
make it work on Windows.
Change-Id: I21011ed4f619f920c53f7cfc3afaa32dc2c0ff4e

0 files changed, 0 insertions, 0 deletions