Remove __bb_init_func and __bb_exit_func [BZ #21974]

__bb_init_func and __bb_exit_func have been removed from GCC 3.3 in
2002 by

https://gcc.gnu.org/ml/gcc-patches/2002-09/msg00499.html

which also recommended that they should also be removed from glibc. These
functions exist only in libc.a and are used for gcov from versions of GCC
older than GCC 3.3.

	[BZ #21974]
	* gmon/Makefile (routines): Remove bb_init_func and
	bb_exit_func.
	(elide-routines.os): Removed.
	* include/sys/gmon.h (__bb): Likewise.
	(__bb_init_func): Likewise.
	(__bb_exit_func): Likewise.