[gdb/testsuite] Fix internal buffer full error in gdb.base/info-types.exp

[gdb/testsuite] Fix internal buffer full error in gdb.base/info-types.exp

With test-case gdb.base/info-types.exp, I run into:
...
ERROR: internal buffer is full.
UNRESOLVED: gdb.base/info-types.exp: l=c: info types
ERROR: internal buffer is full.
UNRESOLVED: gdb.base/info-types.exp: l=c++: info types
...

Fix this by using exp_continue while matching the output of "info types".

Tested on x86_64-linux, using make targets check and check-read1.

gdb/testsuite/ChangeLog:

2020-03-12  Tom de Vries  <tdevries@suse.de>

	* gdb.base/info-types.exp: Use exp_continue during matching of output
	of "info types".