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: Emilia Käsper <emilia@openssl.org>

util/ck_errf.pl

diff --git a/util/ck_errf.pl b/util/ck_errf.pl
index 1a8665a..922e5f6 100755
--- a/util/ck_errf.pl
+++ b/util/ck_errf.pl
@@ -21,7 +21,7 @@
 	$func="";
 	while (<IN>)
 		{
-		if (!/;$/ && /^\**([a-zA-Z].*[\s*])?([A-Za-z_0-9]+)\(.*([),]|$)/)
+		if (!/;$/ && /^\**([a-zA-Z_].*[\s*])?([A-Za-z_0-9]+)\(.*([),]|$)/)
 			{
 			/^([^()]*(\([^()]*\)[^()]*)*)\(/;
 			$1 =~ /([A-Za-z_0-9]*)$/;