configure: make AR and RANLIB customizable

configure

@@ -172,6 +172,8 @@ case "$arg" in
 --host=*|--target=*) target=${arg#*=} ;;
 --build=*) build=${arg#*=} ;;
 -* ) echo "$0: unknown option $arg" ;;
+AR=*) AR=${arg#*=} ;;
+RANLIB=*) RANLIB=${arg#*=} ;;
 CC=*) CC=${arg#*=} ;;
 CFLAGS=*) CFLAGS=${arg#*=} ;;
 CPPFLAGS=*) CPPFLAGS=${arg#*=} ;;
@@ -734,6 +736,8 @@ cat << EOF
 # This version of config.mak was generated by:
 # $cmdline
 # Any changes made here will be lost if configure is re-run
+AR = ${AR:-\$(CROSS_COMPILE)ar}
+RANLIB = ${RANLIB:-\$(CROSS_COMPILE)ranlib}
 ARCH = $ARCH
 SUBARCH = $SUBARCH
 ASMSUBARCH = $ASMSUBARCH