git: Do not install git cvsserver and git svn by default

git: Do not install git cvsserver and git svn by default

These git commands require Perl modules that do not exist in OE-Core.
Add PACKAGECONFIGs to enable them. Be aware though that if you enable
them you must also provide the missing dependencies.

Signed-off-by: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>