and add a new helper target and script, "show-buildlink3", that outputs
a listing of the buildlink3.mk files included as well as the depth at
which they are included.
For example, "make show-buildlink3" in fonts/Xft2 displays:
zlib
fontconfig
iconv
zlib
freetype2
expat
freetype2
Xrender
renderproto
the pkglint warning:
As {INSTALL,DEINSTALL}_TEMPLATE is modified using "+=", its name
should indicate plural.
This does make the variables a bit more suggestive of the fact that they
hold lists of values.
