ETCH-275 Fixed SRuntimes Mutex unlock in Code generation

The Static SRuntimes Mutex is not unlocked on every Error-Case and
resolves to deadlocks.

Change-Id: If224cfb273a8627a8e74f1605a863c3b02743d19

git-svn-id: https://svn.apache.org/repos/asf/etch/trunk@1547309 13f79535-47bb-0310-9956-ffa450edef68