trace: fix a regex portability problem

The /bin/sh in Milax has problems with the regex:
Error: invalid trace backend
Please choose a supported trace backend.

Fix it by escaping ')' like the regexes with '('.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

tracetool

@@ -39,7 +39,7 @@ get_args()
 {
     local args
     args=${1#*\(}
-    args=${args%)*}
+    args=${args%\)*}
     echo "$args"
 }