configure: handle Apple's armv7s in probe_arm_arch()

configure

@@ -3198,6 +3198,7 @@ elif enabled arm; then
         elif check_arm_arch 6T2;      then echo armv6t2;
         elif check_arm_arch 7;        then echo armv7;
         elif check_arm_arch 7A  7_A;  then echo armv7-a;
+        elif check_arm_arch 7S;       then echo armv7-a;
         elif check_arm_arch 7R  7_R;  then echo armv7-r;
         elif check_arm_arch 7M  7_M;  then echo armv7-m;
         elif check_arm_arch 7EM 7E_M; then echo armv7-m;