darwin: mklib: Use lipo rather than file to figure out architectures of object files

(cherry picked from commit ad7f9d71e2)

bin/mklib

@@ -724,22 +724,10 @@ case $ARCH in
 
 	    # examine first object to determine ABI
     	    set ${OBJECTS}
-            ABI_PPC=`file $1 | grep ' ppc'`
-            ABI_I386=`file $1 | grep ' i386'`
-            ABI_PPC64=`file $1 | grep ' ppc64'`
-            ABI_X86_64=`file $1 | grep ' x86_64'`
-            if [ "${ABI_PPC}" ] ; then
-                OPTS="${OPTS} -arch ppc"
-            fi
-            if [ "${ABI_I386}" ] ; then
-                OPTS="${OPTS} -arch i386"
-            fi
-            if [ "${ABI_PPC64}" ] ; then
-                OPTS="${OPTS} -arch ppc64"
-            fi
-            if [ "${ABI_X86_64}" ] ; then
-                OPTS="${OPTS} -arch x86_64"
-            fi
+            ABIS=`lipo -info $1 | sed s/.*://`
+            for ABI in $ABIS; do
+                OPTS="${OPTS} -arch ${ABI}"
+            done
 
             if [ "${ALTOPTS}" ] ; then
                 OPTS=${ALTOPTS}