winapi: Get the list of files from git-ls-files if possible.

tools/winapi/options.pm

@@ -236,6 +236,13 @@ sub parse_files($) {
 	}
     }
 
+    if($#c_files == -1 && $#h_files == -1 && $#paths == -1 && -d ".git")
+    {
+	@$c_files = sort split /\0/, `git ls-files -z \\*.c`;
+	@$h_files = sort split /\0/, `git ls-files -z \\*.h`;
+    }
+    else
+    {
         if($#c_files == -1 && $#h_files == -1 && $#paths == -1)
         {
             @paths = ".";
@@ -269,6 +276,7 @@ sub parse_files($) {
                 }
                              } split(/\n/, `$h_command`));
         }
+    }
 
     my %dirs;
     foreach my $file (@$c_files, @$h_files) {