Switch to non-greedy match so that subject CN extraction gets the lea…

…st significant CN in cases where there is more than one CN (the jiscmail certificate looks like this, it turns out).

build/check_embedded.pl

@@ -67,7 +67,7 @@
 					$issuerCN = $issuer;
 				}
 			}
-			if (/^\s*Subject:\s*.*CN=([a-z0-9\-\.]+).*$/) {
+			if (/^\s*Subject:\s*.*?CN=([a-z0-9\-\.]+).*$/) {
 				$subjectCN = $1;
 				# print "subjectCN = $subjectCN\n";
 			}