configure: support conditional compile of efl and extensions

configure: support conditional compile of efl and extensions

Add --[disable|enable]-efl-tests to allow user to conditionally
compile the efl tests.  Without an explicit option specified by
the user, then autodetect whether efl tests can be compiled.

Add --[disable|enable]-weston-extensions to allow the user to
conditionally compile the weston wfits extension.  Without an
explicit option specified by the useer, then autodetect whether
the weston extensions can be compiled.

Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>