[gdb/testsuite] Run read1 timeout tests with with_read1_timeout_factor

[gdb/testsuite] Run read1 timeout tests with with_read1_timeout_factor

When running tests with check-read1, we run into some timeouts where the tests
are not easy to rewrite using gdb_test_sequence:
...
FAIL: gdb.base/help.exp: help data (timeout)
FAIL: gdb.base/help.exp: help files (timeout)
FAIL: gdb.base/help.exp: help internals (timeout)
FAIL: gdb.base/help.exp: help user-defined (timeout)
FAIL: gdb.base/help.exp: help breakpoint "b" abbreviation (timeout)
FAIL: gdb.base/help.exp: help breakpoint "br" abbreviation (timeout)
FAIL: gdb.base/help.exp: help breakpoint "bre" abbreviation (timeout)
FAIL: gdb.base/info-macros.exp: info macros 2 (timeout)
FAIL: gdb.base/info-macros.exp: next (timeout)
FAIL: gdb.base/info-macros.exp: info macros 3 (timeout)
FAIL: gdb.base/info-macros.exp: next (timeout)
FAIL: gdb.base/info-macros.exp: next (timeout)
FAIL: gdb.base/info-macros.exp: info macros (timeout)
FAIL: gdb.base/info-macros.exp: next (timeout)
FAIL: gdb.base/info-macros.exp: next (timeout)
FAIL: gdb.base/info-macros.exp: info macros 7 (timeout)
FAIL: gdb.cp/nested-types.exp: ptype S10 (limit = -1) // parse failed (timeout)
FAIL: gdb.cp/nested-types.exp: set print type nested-type-limit 1 (timeout)
...

Fix these by increasing the timeout by a factor 10.

Tested on x86_64-linux.

gdb/testsuite/ChangeLog:

2019-08-05  Tom de Vries  <tdevries@suse.de>

	PR testsuite/24863
	* lib/gdb.exp (with_read1_timeout_factor): New proc.
	* gdb.base/help.exp: Use with_read1_timeout_factor.
	* gdb.base/info-macros.exp: Same.
	* gdb.cp/nested-types.exp: Same.