Refactor named group handling for conditional tests.


git-svn-id: svn://vcs.exim.org/pcre/code/trunk@1365 2f5784b3-3f2a-0410-8824-cb99058d5e15
Forgot to commit this for the previous commit.


git-svn-id: svn://vcs.exim.org/pcre/code/trunk@1366 2f5784b3-3f2a-0410-8824-cb99058d5e15