[gdb/testsuite] Fix gdb.fortran/info-types.exp regexp

[gdb/testsuite] Fix gdb.fortran/info-types.exp regexp

The gdb.fortran/info-types.exp test-case passes with gcc 7 (though not on
openSUSE, due to the extra debug info) and fails with gcc 4.8 and gcc 8.

Fix the gdb_test regexp to fix all those cases.

gdb/testsuite/ChangeLog:

2019-08-29  Tom de Vries  <tdevries@suse.de>

	* gdb.fortran/info-types.exp: Fix gdb_test regexp to allow more
	diverse debug info.
	* lib/fortran.exp (fortran_int8): New proc, based on fortran_int4.