Review and fix regular expressions of the form /^foo|bar$/.
Replace regular expressions with simple string comparisons where
possible.
Use '(?:subregexp)' instead of '(subregexp)' wherever possible.
'dlls/gdi' does not have a win16drv subdirectory anymore so simplify
regular expressions accordingly.

diff --git a/tools/winapi/winapi.pm b/tools/winapi/winapi.pm
index 3e9d793..256e88f 100644
--- a/tools/winapi/winapi.pm
+++ b/tools/winapi/winapi.pm
@@ -442,7 +442,7 @@
             } else {
                 $$module_external_calling_convention{$module}{"\@$ordinal"} = "extern";
             }
-	} elsif(/^(\d+|@)\s+(equate|variable)/) {
+	} elsif(/^(?:\d+|@)\s+(?:equate|variable)/) {
 	    # ignore
 	} else {
 	    my $next_line = <IN>;