[PATCH] winebuild: Allow using clang for as command.

[Jacek Caban]

Since a9b5bb326a1514e2c4185633ab34b22c9bbc9863, Wine needs 
get_as_command to work without cc_command available. While as is usually 
a GCC dependency, Clang toolchains may not contain it.

Signed-off-by: Jacek Caban <jacek(a)codeweavers.com>
---
I noticed it with Android builds. We could also pass --cc-cmd with 
makedep, but making winebuild more flexible seems interesting on its own.

  tools/winebuild/utils.c | 35 ++++++++++++++++++++++++++---------
  1 file changed, 26 insertions(+), 9 deletions(-)