Expand tilde used in command-line arguments

This enables one to specify e.g. --with-opm-core=~/opm/bld/opm-core

configure

@@ -133,6 +133,8 @@ while getopts -- ":-:" optchar; do
             CMAKE_COMMAND="${pkgloc}"
             break
           fi
+          # tilde expansion; quote safely before running eval on it
+          eval pkgloc=$(printf "%q" "${pkgloc}")
           # expand to full path since CMake changes to source directory (!)
           # this also normalize the path name wrt. not having a trailing slash
           pkgloc=$(test -d "${pkgloc}" && sh -c "cd \"${pkgloc}\"; pwd")