graphics/librsvg2: the port had been updated to version 2.40.23
- Switch to USE_GITLAB/GL_* because it is tagged-only release
- Drop needless GNU_CONFIGURE_MANPREFIX and `localbase' from the USES list
- Rewrite regex in `post-patch' target so it produces identical result, but is shorter and more correct (escape the dot)
- Drop the DOCS option which does nothing after HTML files and images no longer come with the distfile and USES+=gnomeprefix forces the --disable-gtk-doc anyway (however, dependency on textproc/gtk-doc is required for GTK_DOC_CHECK macro in the configure.ac, so keep it but adjust accordingly)
PR: 295743
Reviewed by: arrowd