[gdb/testsuite] Fix gdb.opt/solib-intra-step.exp with -m32 and gcc-10

[gdb/testsuite] Fix gdb.opt/solib-intra-step.exp with -m32 and gcc-10

When running test-case gdb.opt/solib-intra-step.exp with target board
unix/-m32 and gcc-10, I run into:
...
(gdb) step^M
__x86.get_pc_thunk.bx () at ../sysdeps/i386/crti.S:68^M
68      ../sysdeps/i386/crti.S: No such file or directory.^M
(gdb) step^M
shlib_second (dummy=0) at solib-intra-step-lib.c:23^M
23        abort (); /* second-hit */^M
(gdb) FAIL: gdb.opt/solib-intra-step.exp: second-hit
...

The problem is that the test-case expects to step past the retry line,
which is optional.

Fix this by removing the state tracking logic from the gdb_test_multiples.  It
makes the test more difficult to understand, and doesn't specifically test for
faulty gdb behaviour.

Tested on x86_64-linux.

gdb/testsuite/ChangeLog:

2021-01-29  Tom de Vries  <tdevries@suse.de>

	* gdb.opt/solib-intra-step.exp: Remove state tracking logic.