[ARM] PR target/70830: Avoid POP-{reglist}^ when returning from interrupt handlers

[ARM] PR target/70830: Avoid POP-{reglist}^ when returning from interrupt handlers

	PR target/70830
	* config/arm/arm.c (arm_output_multireg_pop): Avoid POP instruction
	when popping the PC and within an interrupt handler routine.
	Add missing tab to output of "ldmfd".
	(output_return_instruction): Output LDMFD with SP update rather
	than POP when returning from interrupt handler.

	* gcc.target/arm/interrupt-1.c: Change dg-compile to dg-assemble.
	Add -save-temps to dg-options.
	Scan for ldmfd rather than pop instruction.
	* gcc.target/arm/interrupt-2.c: Likewise.
	* gcc.target/arm/pr70830.c: New test.

From-SVN: r236169