Fixup native builds on powerpc

When we changed ARCH from ppc to powerpc we need to treat HOSTARCH the
same way.  We use HOSTARCH == ARCH to determine if a build is native.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

Makefile

@@ -38,9 +38,9 @@ HOSTARCH := $(shell uname -m | \
 	    -e s/sun4u/sparc64/ \
 	    -e s/arm.*/arm/ \
 	    -e s/sa110/arm/ \
-	    -e s/powerpc/ppc/ \
-	    -e s/ppc64/ppc/ \
-	    -e s/macppc/ppc/)
+	    -e s/ppc64/powerpc/ \
+	    -e s/ppc/powerpc/ \
+	    -e s/macppc/powerpc/)
 
 HOSTOS := $(shell uname -s | tr '[:upper:]' '[:lower:]' | \
 	    sed -e 's/\(cygwin\).*/cygwin/')