This fixes a GCC-8 regression that we accidentally switched off frame
pointers in the AArch64 backend when changing the defaults in the common
parts of the code. This breaks an ABI decision that was made in GCC at
the dawn of the port with respect to having a frame pointer at all
times.  If we really want to turn this off lets have a discussion around
that separately.

For now turn this back on and I believe this will leave PR84521 latent
again with -fomit-frame-pointer and (hopefully) make the ruby issue go
away. I'm asking Sudi to pick that up.

Bootstrapped and regression tested on AArch64-none-linux-gnu but I see
one regression in gcc.c-torture/execute/960419-2.c which needs to be
looked at next (PR84528, thanks Kyrill).

Ok to put in and then look at PR84528 ?

2018-02-26  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>

        PR target/84521
	* common/config/aarch64/aarch64-common.c
	(aarch_option_optimization_table[]): Switch
	off fomit-frame-pointer

2018-02-26  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>

	PR target/84521
	* gcc.target/aarch64/lr_free_2.c: Revert changes in
	r254814 disabling -fomit-frame-pointer by default.
	* gcc.target/aarch64/spill_1.c: Likewise.
	* gcc.target/aarch64/test_frame_11.c: Likewise.
	* gcc.target/aarch64/test_frame_12.c: Likewise.
	* gcc.target/aarch64/test_frame_13.c: Likewise.
	* gcc.target/aarch64/test_frame_14.c: Likewise.
	* gcc.target/aarch64/test_frame_15.c: Likewise.
	* gcc.target/aarch64/test_frame_3.c: Likewise.
	* gcc.target/aarch64/test_frame_5.c: Likewise.
	* gcc.target/aarch64/test_frame_9.c: Likewise.

From-SVN: r257984