aarch64: Remove broken CFLAGS in configure

GCC doesn't have an "-arch" switch, but works when that entire line is removed.

configure

@@ -840,9 +840,6 @@ if [ $asm = auto -a $ARCH = ARM ] ; then
 fi
 
 if [ $asm = auto -a $ARCH = AARCH64 ] ; then
-    # set flags so neon is built by default
-    echo $CFLAGS | grep -Eq '(-mcpu|-march|-mfpu|-arch)' || CFLAGS="$CFLAGS -arch arm64 -mfpu=neon"
-
     if  cc_check '' '' '__asm__("cmeq v0.8h, v0.8h, #0");' ; then define HAVE_NEON
         ASFLAGS="$ASFLAGS -c"
     else