Allow for types with leading underscore when checking error macros.

We have an increasing number of function declarations starting with
'__owur'.  Unfortunately, util/ck_errf.pl fails to detect them.  A
simple change fixes that issue.
Reviewed-by: NEmilia Käsper <emilia@openssl.org>

util/ck_errf.pl

@@ -21,7 +21,7 @@ foreach $file (@ARGV)
 	$func="";
 	while (<IN>)
 		{
-		if (!/;$/ && /^\**([a-zA-Z].*[\s*])?([A-Za-z_0-9]+)\(.*([),]|$)/)
+		if (!/;$/ && /^\**([a-zA-Z_].*[\s*])?([A-Za-z_0-9]+)\(.*([),]|$)/)
 			{
 			/^([^()]*(\([^()]*\)[^()]*)*)\(/;
 			$1 =~ /([A-Za-z_0-9]*)$/;