Change the timers Makefile to make use of shared run and install logic
in lib.mk. Destructive tests are installed but not run by default.

Add a new variable, TEST_PROGS_EXTENDED, which is a list of extra
programs to install, but which are not run by the default run_tests
logic.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>