arm: Fix handler-align.c testcase [PR target/94743]

This testcase triggers the new warning, so compile it with
-mgeneral-regs-only.

2020-07-01  Christophe Lyon  <christophe.lyon@linaro.org>

	PR target/94743

	gcc/testsuite/
	* gcc.target/arm/handler-align.c: Add -mgeneral-regs-only.

gcc/testsuite/gcc.target/arm/handler-align.c

@@ -1,6 +1,6 @@
 /* Test epilogue of a realigned interrupt handler. */
 /* { dg-do run } */
-/* { dg-options "-mthumb -Os" } */
+/* { dg-options "-mthumb -Os -mgeneral-regs-only" } */
 /* { dg-skip-if "" { ! { arm_thumb1_ok || arm_thumb2_ok } } } */
 /* { dg-require-effective-target arm_cortex_m } */
 /* { dg-require-effective-target arm_eabi } */