www/node[45]: work around build breakages due to include path ordering

Add a post-configure step to strip out all occurrences of
-I${LOCALBASE}/include. Rely instead on USES+=localbase to tell the
compiler where to find includes from external dependencies.

After r416894, node.js builds will use external dependencies instead of
bundled ones. Fallout from this changes includes several build
breakages. All come from the fact that the node-gyp build process adds
-I${LOCALBASE}/include to CFLAGS before all others, including its own
bundled dependencies. This causes the build to incorrectly pick up
include files from any packages in ${LOCALBASE}, rather than the bundled
libraries as intended.

PR: 210618
Submitted by: Bradley T. Hughes <bradleythughes@fastmail.fm> (maintainer)