Enables gdb.reverse testsuite for aarch64*-linux targets

Enables gdb.reverse testsuite for aarch64*-linux targets

This patch enable gdb.reverse tests for aarch64*-linux targets.

With this patch, there are 7 FAILs in gdb.reverse/ tests.

 FAIL: gdb.reverse/finish-reverse-bkpt.exp: reverse-finish from void_func trips breakpoint at entry
 FAIL: gdb.reverse/finish-reverse-bkpt.exp: no spurious proceed after breakpoint stop
 FAIL: gdb.reverse/next-reverse-bkpt-over-sr.exp: reverse-next over call trips user breakpoint at function entry
 FAIL: gdb.reverse/step-precsave.exp: reverse step into fn call
 FAIL: gdb.reverse/step-precsave.exp: reverse step out of called fn
 FAIL: gdb.reverse/step-reverse.exp: reverse step into fn call
 FAIL: gdb.reverse/step-reverse.exp: reverse step out of called fn

gdb/testsuite:

2015-05-26  Omair Javaid  <omair.javaid@linaro.org>

	* lib/gdb.exp (supports_process_record): Return true for aarch64*-linux*.
	(supports_reverse): Likewise.