Add support for SUBTARGET_OVERRIDE_OPTIONS on aarch64

	* config/aarch64/aarch64.c (aarch64_override_options): Once arch,
	cpu and tune were validated, insert SUBTARGET_OVERRIDE_OPTIONS if
	defined.

From-SVN: r267060

gcc/ChangeLog

 2018-12-12  Olivier Hainque  <hainque@adacore.com>
 
+	* config/aarch64/aarch64.c (aarch64_override_options): Once arch,
+	cpu and tune were validated, insert SUBTARGET_OVERRIDE_OPTIONS if
+	defined.
+
+2018-12-12  Olivier Hainque  <hainque@adacore.com>
+
 	* config/aarch64/aarch64.c (PROBE_STACK_FIRST_REG) : Redefine as
 	R9_REGNUM instead of 9.
 	(PROBE_STACK_SECOND_REG): Redefine as R10_REGNUM instead of 10.

gcc/config/aarch64/aarch64.c

@@ -11408,6 +11408,10 @@ aarch64_override_options (void)
   if (aarch64_tune_string)
     valid_tune = aarch64_validate_mtune (aarch64_tune_string, &selected_tune);
 
+#ifdef SUBTARGET_OVERRIDE_OPTIONS
+  SUBTARGET_OVERRIDE_OPTIONS;
+#endif
+
   /* If the user did not specify a processor, choose the default
      one for them.  This will be the CPU set during configuration using
      --with-cpu, otherwise it is "generic".  */