Don't call clock_getres in sysconf.
There are a hundred other reasons why we can't run on kernels old enough
to not have all the clocks covered by sysconf.
This was causing trouble for jemalloc 4.1.0 in a seccomp-constrained process
because jemalloc 4.1.0 introduced a call to sysconf that caused us to make
clock_getres syscalls for the first time, leading to SIGSYS.
Bug: http://b/
27408522
(cherry picked from commit
d2b8de2cd16ecd86c830d98c58bcf392475bd0b3)
Change-Id: Id46a0f2c2804c597a8c9091690a8a1fc4a65f4cd