[gdb/testsuite] Fix info-types-c.exp

[gdb/testsuite] Fix info-types-c.exp

Recently, I've rewritten gdb.base/info-types.exp.tcl to do processing
line-by-line (commit 2129a942553).

When building gdb with -O0, this test passes for me, but with -O2 I sometimes
run into:
...
FAIL: gdb.base/info-types-c.exp: info types (state == 1)
...

The output the failing gdb_test_multiple is trying to parse is:
...
(gdb) info types^M
All defined types:^M
^M
File src/gdb/testsuite/gdb.base/info-types.c:^M
52:     typedef enum {...} anon_enum_t;^M
  ...
(gdb)
...
and the FAIL with state == 1 means that:
- the regexp for "All defined types:" did trigger, and that
- the regexp for "File .*info-types.c" didn't trigger.

This is due to the fact that the empty line inbetween is supposed to be
matched by the "random line" regexp "^\r\n(\[^\r\n\]*)(?=\r\n)", which doesn't
happen because instead the earlier regexp consuming the gdb prompt matches.

Fix this by moving the "random line" regexp up.  [ Note that that regexp does
not consume the gdb prompt, because it requires (but doesn't consume) a
terminating "\r\n".

Tested on x86_64-linux.

gdb/testsuite/ChangeLog:

2021-06-07  Tom de Vries  <tdevries@suse.de>

	* gdb.base/info-types.exp.tcl (run_test): Move "random line" regexp
	up.