config.c: Cleanup AST_INCLUDE_GLOB

* In main/config.c, AST_INCLUDE_GLOB is fixed to '1' making the #ifdefs
  pointless.

* In utils/extconf.c, AST_INCLUDE_GLOB is never defined so there is a
  lot of dead code.

Change-Id: I1bad1a46d7466ddf90d52cc724e997195495226c