x86, powerpc: Remove -funit-at-a-time compiler option entirely

GCC 4.6 manual says:

-funit-at-a-time
This option is left for compatibility reasons. -funit-at-a-time has
no effect, while -fno-unit-at-a-time implies -fno-toplevel-reorder
and -fno-section-anchors. Enabled by default.

Remove it.

Signed-off-by: Masahiro Yamada <[e-mail]>
Signed-off-by: Borislav Petkov <[e-mail]>
Acked-by: Ingo Molnar <[e-mail]>
Acked-by: Michael Ellerman <[e-mail]>
Cc: "H. Peter Anvin" <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Richard Weinberger <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Cc: x86-ml <[e-mail]>
Link: https://lkml.kernel.org/r/[e-mail]

arch/powerpc/Makefile

···
 KBUILD_CFLAGS += $(call cc-option,-mno-spe)
 KBUILD_CFLAGS += $(call cc-option,-mspe=no)
 
-# Enable unit-at-a-time mode when possible. It shrinks the
-# kernel considerably.
-KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)
-
 # FIXME: the module load should be taught about the additional relocs
 # generated by this.
 # revert to pre-gcc-4.4 behaviour of .eh_frame

arch/x86/Makefile

···
 
         KBUILD_CFLAGS += -mno-red-zone
         KBUILD_CFLAGS += -mcmodel=kernel
-
-        # -funit-at-a-time shrinks the kernel .text considerably
-        # unfortunately it makes reading oopses harder.
-        KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)
 endif
 
 ifdef CONFIG_X86_X32

arch/x86/Makefile.um

···
 # an unresolved reference.
 cflags-y += -ffreestanding
 
-# gcc 4.3.0 needs -funit-at-a-time for extern inline functions.
-KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)
-
 KBUILD_CFLAGS += $(cflags-y)
 
 else
···
 LINK-$(CONFIG_LD_SCRIPT_DYN) += -Wl,-rpath,/lib64
 LINK-y += -m64
 
-# Do unit-at-a-time unconditionally on x86_64, following the host
-KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)
 endif