ver_linux: Eliminate duplicate code in ldconfig processing logic

The code that acquires the version strings for libc and libcpp is
identical, as is the printversion call. The only difference being the
name of the library being printed.

Refactor the code by unifying the bits that are common to both libraries.

Signed-off-by: Alexander Kapshuk <alexander.kapshuk@gmail.com>
Link: https://lore.kernel.org/r/20210108112626.8623-1-alexander.kapshuk@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>