Enable semantic when running with GNU Emacs CEDET.

GNU Emacs CEDET uses a semantic-mode global minor mode with
a mapping of major-mode to set up functions. This is incompatible
with the upstream CEDET 1.x distributions.

For upstream CEDET: switch from obsolete semantic-init-hooks to the
new semantic-init-hook.

git-svn-id: https://jdee.svn.sourceforge.net/svnroot/jdee/trunk@282 381a1f10-3442-0410-997e-ef331cd04102