kbuild: allow assignment to {A,C,LD}FLAGS_MODULE on the command line

It is now possible to assign options to AS, CC and LD
on the command line - which is only used when building modules.

{A,C,LD}FLAGS_MODULE was all used both in the top-level Makefile
in the arch makefiles, thus users had no way to specify
additional options to AS, CC, LD when building modules
without overriding the original value.

Introduce a new set of variables KBUILD_{A,C,LD}FLAGS_MODULE
that is used by arch specific files and free up
{A,C,LD}FLAGS_MODULE so they can be assigned on
the command line.

All arch Makefiles that used the old variables has been updated.

Note: Previously we had a MODFLAGS variable for both
AS and CC. But in favour of consistency this was dropped.
So in some cases arch Makefile has one assignmnet replaced by
two assignmnets.

Note2: MODFLAGS was not documented and is dropped
without any notice. I do not expect much/any breakage
from this.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Chen Liqin <liqin.chen@sunplusct.com>
Acked-by: Mike Frysinger <vapier@gentoo.org> [blackfin]
Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> [avr32]
Signed-off-by: Michal Marek <mmarek@suse.cz>
diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index 1893efd..a77dcf3 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -93,7 +93,8 @@
 cflags-y			+= -G 0 -mno-abicalls -fno-pic -pipe
 cflags-y			+= -msoft-float
 LDFLAGS_vmlinux			+= -G 0 -static -n -nostdlib
-MODFLAGS			+= -mlong-calls
+KBUILD_AFLAGS_MODULE		+= -mlong-calls
+KBUILD_CFLAGS_MODULE		+= -mlong-calls
 
 cflags-y += -ffreestanding
 
@@ -172,7 +173,8 @@
 
 ifdef CONFIG_CPU_SB1
 ifdef CONFIG_SB1_PASS_1_WORKAROUNDS
-MODFLAGS	+= -msb1-pass1-workarounds
+KBUILD_AFLAGS_MODULE += -msb1-pass1-workarounds
+KBUILD_CFLAGS_MODULE += -msb1-pass1-workarounds
 endif
 endif