CMake Nightly Date Stamp
CMake: Skip empty link.txt lines (#13845)

In the implementation of "cmake -E cmake_link_script", skip lines from
the input file that are empty or contain only whitespace.  Do not try to
run a child with no command line.
Merge topic 'fix-empty-link-line-crash' into next

8ff1d47 CMake: Skip empty link.txt lines (#13845)
5929086 CMake Nightly Date Stamp