Update 15.3 renamed redist directory from 150 to 141 and introduced
intermediate build number directories, that are different from the
compiler build number directories.

While the compiler is located under:

  [...]/MSVC/14.11.25503/bin/HostX64/x64/cl.exe

the merge modules are located now under:

  VC/redist/MSVC/14.11.25325/MergeModules

Change the hard coded detection approach, to the dynamic one: list
all directories in suspected locations and check for existnace of
the artifacts we are looking for.

Change-Id: Ie040f290d1748ab4ec5c715b6636cc3733329e1c
Reviewed-on: https://gerrit.libreoffice.org/41922Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>
Tested-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>