Use new tail-calling mechanism on ARM.

Use new tail-calling mechanism on ARM.
* arm.md (sibcall, sibcall_value): New expands.
(sibcall_insn, sibcall_value_insn, sibcall_epilogue): New insns.
(tailcalling peepholes): Delete.
(push_multi): Simplify.
* arm.c (lr_save_eliminated): Delete definition.
(pattern_really_clobbers_lr, function_really_clobbers_lr): Delete.
(output_return_instruction): Remove checks on lr_save_eliminated.
(output_arm_prologue): Remove old tail-calling code.
(arm_output_epilogue): New parameter, really_return.  All callers
changed.  Handle tail-calling epilogues.
* arm.h (lr_save_eliminated): Delete declaration.
(frame_pointer_needed): Delete declaration.
* arm-protos.h (arm_output_epilogue): Adjust prototype.

* arm.md (is_thumb): Examine symbol thumb_code, not expression
TARGET_ARM.
* arm.c (thumb_code): Define it.
(arm_override_options): Set it.
* arm.h (thumb_code): Declare it.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@33731 138bc75d-0d04-0410-961f-82ee72b054a4