always use codeview (pdb) when object_format is PE/COFF
always use codeview (pdb) when object_format is PE/COFF

Previously, when mixing Zig and C/C++ code for windows-gnu targets, zig
would get codeview format but the C/C++ code would not get any debug
info. Now, C/C++ code properly emits debug info in codeview format and
everything just works.

zig-lang/zig,raulgrell/zig,raulgrell/zig,andrewrk/zig,raulgrell/zig,zig-lang/zig,andrewrk/zig,raulgrell/zig,zig-lang/zig,raulgrell/zig