[gdb/testsuite] Fix gdb.reverse/consecutive-{precsave,reverse}.exp with gcc-8

[gdb/testsuite] Fix gdb.reverse/consecutive-{precsave,reverse}.exp with gcc-8

When running test-cases gdb.reverse/consecutive-precsave.exp and
gdb.reverse/consecutive-reverse.exp with gcc-8, we get:
...
FAIL: gdb.reverse/consecutive-precsave.exp: stopped at bp, 2nd instr
FAIL: gdb.reverse/consecutive-reverse.exp: stopped at bp, 2nd instr
...

These FAILs are duplicates of the FAILs fixed in commit 7c99e7e2b08
"[gdb/testsuite] Fix gdb.base/consecutive.exp with gcc-8".

Fix these in the same manner.

Tested on x86_64-linux.

gdb/testsuite/ChangeLog:

2020-05-06  Tom de Vries  <tdevries@suse.de>

	* gdb.reverse/consecutive-precsave.exp: Handle if instruction after
	breakpoint is at a "recommended breakpoint location".
	* gdb.reverse/consecutive-reverse.exp: Same.