cc/gcc: allow CC_EXTRA_CONFIG_ARRAY on baremetal

The final bare-metal compiler is built using the core backend.
Currently the core uses the CC_CORE_EXTRA_CONFIG_ARRAY variable.

While this works as supposed to, this can leave the user puzzled
in the menuconfig, since all he can see is the core options, not
the final options.

Only show the core options if any of the core passes are needed,
and use the final options in the core-backend if we're issuing
the bare-metal compiler.

Signed-off-by: Cody P Schafer <dev@codyps.com>
[yann.morin.1998@free.fr: hide core options if no core pass needed;
use final option in core backend if issuing the bare-metal compiler]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Message-Id: <22181e546ba746202489.1399688067@localhost>
Patchwork-Id: 347586

 Prevent erroneous inline optimization of initfini.s on PowerPC64.

 The problem and the fix was reported there:

 http://sourceware.org/ml/libc-alpha/2012-01/msg00195.html

 Git commit:

 commit 1fe05ea95e1460e5e1cf1568a8ce3982f0f02de6

 Author: Ryan S. Arnold <rsa@us.ibm.com>

 Date: Tue May 3 17:26:17 2011 -0500

 --- glibc.orig/sysdeps/powerpc/powerpc64/Makefile	2012-12-22 19:10:06.713568781 -0800

 +++ glibc/sysdeps/powerpc/powerpc64/Makefile	2012-12-22 19:10:50.318605517 -0800

 @@ -31,7 +31,7 @@

  ifneq ($(elf),no)

  # The initfini generation code doesn't work in the presence of -fPIC, so

  # we use -fpic instead which is much better.

 -CFLAGS-initfini.s += -fpic -O1

 +CFLAGS-initfini.s += -fpic -O1 -fno-inline

  endif

  endif