In addition to adding ast.po to the repository, your patch will have to add ast.po to po/Makefile.in.
Also, please change the comment at the top of the PO file to match the comments in the existing Wine PO files, and put your name in gettext's Last-Translator header the same as in Git's Signed-off-by header.
You might have to create dlls/kernel32/nls/ast.nls for your translations to appear in Wine programs. Please compile Wine and double-check that your translation looks correct in practice before sending the patch.
-Alex