[binutils-gdb] ARM: Do not use FP reg when on AAPCS

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*** TEST RESULTS FOR COMMIT 9e237747bd1fd7b371fed5edb91dd9baace4b2dc ***

Author: Marius Muench <marius.muench@eurecom.fr>
Branch: master
Commit: 9e237747bd1fd7b371fed5edb91dd9baace4b2dc

ARM: Do not use FP reg when on AAPCS

GDB tries to dereference the frame pointer in arm_scan_prologue as a
last resort to create frame information.
However, the more recent AAPCS ABI does not make use of a frame pointer.

This patch checks whether the specified arm_abi is AAPCS before
dereferencing the "frame pointer". If so, just return as efforts to use
it for restoring frame information won't work.

gdb/ChangeLog
2018-11-06  Marius Muench  <marius.muench@eurecom.fr>

	* arm-tdep.c (arm_scan_prologue): Don't dereference FP reg
	when on AAPCS.