sipmsg_validate(): Allow "(" and ")" in SIP URI usernames

According to RFC 3261:
    mark        =  "-" / "_" / "." / "!" / "~" / "*" / "'"
                   / "(" / ")"

... so both parantheses are legal within URI usernames.

(cherry picked from commit c82d074)

modules/sipmsgops/sipmsgops.c

@@ -1410,8 +1410,8 @@ static char _is_username_char[128] = {
 	0 /* 37 % */,
 	1 /* 38 & */,
 	1 /* 39 ' */,
-	0 /* 40 ( */,
-	0 /* 41 ) */,
+	1 /* 40 ( */,
+	1 /* 41 ) */,
 	1 /* 42 * */,
 	1 /* 43 + */,
 	1 /* 44 , */,