print/lilypond-devel: update 2.19.48 -> 2.19.51

PR: 213656
Changes: http://git.savannah.gnu.org/gitweb/?p=lilypond.git;a=log;h=refs/tags/release/2.19.51-1
Submitted by: Martin Neubauer <m.ne@gmx.net> (maintainer)