xz: Enable BCJ filters on SPARC and 32-bit x86

The BCJ filters were meant to be enabled already on these
archs, but the xz_wrap.sh script was buggy. Enabling the
filters should give smaller kernel images.

xz_wrap.sh will now use $SRCARCH instead of $ARCH to detect
the architecture. That way it doesn't need to care about the
subarchs (like i386 vs. x86_64) since the BCJ filters don't
care either.

Signed-off-by: Lasse Collin <[e-mail]>
Acked-by: Jan Beulich <[e-mail]>
Acked-by: H. Peter Anvin <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

scripts/xz_wrap.sh

···
 BCJ=
 LZMA2OPTS=
 
-case $ARCH in
-	x86|x86_64)     BCJ=--x86 ;;
+case $SRCARCH in
+	x86)            BCJ=--x86 ;;
 	powerpc)        BCJ=--powerpc ;;
 	ia64)           BCJ=--ia64; LZMA2OPTS=pb=4 ;;
 	arm)            BCJ=--arm ;;