Support standard --prefix and --libdir configure arguments: Closes #6931
Support standard --prefix and --libdir configure arguments: Closes #6931

jimbonator/shotwell,abrauchli/shotwell,ritchiewilson/shotwell,ritchiewilson/shotwell,ritchiewilson/shotwell,jimbonator/shotwell,jimbonator/shotwell,abrauchli/shotwell,abrauchli/shotwell