The new `%s` format specifier is substituted by file()/string()
`TIMESTAMP` sub-commands with the number of seconds since unix-epoch
(1970-01-01 00:00:00 UTC).
Co-Author: Nils Gladitz <nilsgladitz@gmail.com>
Eliminate the platform difference in calling stat. We call stat normally
in other places in the CMake code base just fine. Works everywhere we
work. Will hopefully also fix the Borland Continuous dashboard failure
that is occurring with respect to correctly measuring the modification
time of a freshly generated file.