Fix some duplicate test names

Fix some duplicate test names

While doing a testsuite run on aarch64-linux, I noticed a bunch of duplicated
test name results. It annoyed me a little, so I decided to go ahead and fix the
worst offenders.

The following patch brings the duplicate test names down from 461 to 137.

The remaining ones are mostly scattered across the testsuite, with 1 to 3
duplicates per testcase. We can fix those as we go.

gdb/testsuite/ChangeLog:

2020-05-27  Luis Machado  <luis.machado@linaro.org>

	* gdb.arch/aarch64-sighandler-regs.exp: Fix duplicated test names.
	* gdb.arch/aarch64-tagged-pointer.exp: Likewise.
	* gdb.arch/arm-disassembler-options.exp: Likewise.
	* gdb.arch/arm-disp-step.exp: Likewise.
	* gdb.arch/thumb-prologue.exp: Likewise.
	* gdb.base/async.exp: Likewise.
	* gdb.base/auxv.exp: Likewise.
	* gdb.base/complex-parts.exp: Likewise.
	* gdb.base/ena-dis-br.exp: Likewise.
	* gdb.base/foll-exec.exp: Likewise.
	* gdb.base/permissions.exp: Likewise.
	* gdb.base/relocate.exp: Likewise.
	* gdb.base/return2.exp: Likewise.
	* gdb.base/sigbpt.exp: Likewise.
	* gdb.base/siginfo-obj.exp: Likewise.
	* gdb.cp/converts.exp: Likewise.
	* gdb.cp/exceptprint.exp: Likewise.
	* gdb.cp/inherit.exp: Likewise.
	* gdb.cp/nsnoimports.exp: Likewise.
	* gdb.cp/virtbase2.exp: Likewise.
	* gdb.mi/mi-var-cmd.exp: Likewise.
	* gdb.mi/var-cmd.c: Likewise.