Tests: adjusted proxy variables time checks. Strict ">= 1" check may fail if timekeeping is not precise, and sleep(1) results in something like 0.999 time in headers. In particular, this happens when using clock_gettime(CLOCK_MONOTONIC_COARSE) for ngx_current_msec on Ubuntu 16.04. To fix this, sleep(1) replaced with select(1.1).