pkgbase: move libedit into the -runtime package

libedit isn't as foundational as the rest of -clibs, but various bits
of -runtime do need it. Give it a new home over in -runtime.

This also fixes the libedit build to group the readline bits into the
same package as the libedit that implements them.

Reviewed by: ivy

(cherry picked from commit 5e4e12ae64b3e0377984d22610a6b3d6ccd6cee6)