Compiling these tests still times out too often when running the
testsuite with more parallel jobs than there are available cores.

Signed-off-by: Jonathan Wakely <jwakely@redhat.com>

libstdc++-v3/ChangeLog:

	* testsuite/ext/pb_ds/regression/tree_map_rand.cc: Increase
	timeout factor to 3.
	* testsuite/ext/pb_ds/regression/tree_set_rand.cc: Likewise.

Tested x86_64-linux. Committed to trunk.