Tests: Skip RunCMake.try_compile RerunCMake-nowork case on 1s filesystems

On low-resolution filesystems, Makefile can end up with the same time stamp as CMakeCache.txt. CMake must re-run in this case to be conservative, but that invalidates the -nowork cases.

Rather than trying to detect 1s filesystems, just add an option called CMake_TEST_FILESYSTEM_1S that external scripts can use to tell CMake's test suite about this.

Original Description

Tests: Fix RunCMake.try_compile RerunCMake-nowork case on 1s filesystems

This test writes a file on which re-running CMake depends, runs CMake, and then checks that CMake does not re-run if the file is not modified before the build. Add a delay to ensure that the timestamps on files produced by CMake are newer than the input file even on filesystems with low time resolution.