Support Linux uname-style platform identifier for ppc32.

--- a/configure
+++ b/configure
@@ -398,7 +398,7 @@ if test "x$PLATFORM" = "x"; then
 fi
 
 case $PLATFORM in
-       "macppc"|"Power Macintosh"|"powerpc"|"powerpcspe")
+       "macppc"|"Power Macintosh"|"powerpc"|"powerpcspe"|"ppc")
                RTM_ENABLE="CK_MD_RTM_DISABLE"
                LSE_ENABLE="CK_MD_LSE_DISABLE"
                MM="${MM:-"CK_MD_RMO"}"
