configure: do not bypass cpuflags section if --cpu not given

This will allow arch-specific ways of determining the target
variant when none is specified on the command line.

Signed-off-by: Mans Rullgard <mans@mansr.com>

configure

@@ -2524,10 +2524,7 @@ is_in $arch $ARCH_LIST || warn "unknown architecture $arch"
 enable $arch
 
 # Add processor-specific flags
-if test "$cpu" = generic; then
+if enabled aarch64; then
-    : do nothing
-
-elif enabled aarch64; then
 
     case $cpu in
         armv*)
@@ -2680,8 +2677,10 @@ elif enabled x86; then
 
 fi
 
+if [ "$cpu" != generic ]; then
     add_cflags  $cpuflags
     add_asflags $cpuflags
+fi
 
 # compiler sanity check
 check_exec <<EOF