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.

src/Compilation.zig

@@ -2037,6 +2037,10 @@ pub fn addCCArgs(
 
             if (!comp.bin_file.options.strip) {
                 try argv.append("-g");
+                switch (comp.bin_file.options.object_format) {
+                    .coff, .pe => try argv.append("-gcodeview"),
+                    else => {},
+                }
             }
 
             if (comp.haveFramePointer()) {