This changes the buildlink3.mk files to use an include guard for the
recursive include. The use of BUILDLINK_DEPTH, BUILDLINK_DEPENDS,
BUILDLINK_PACKAGES and BUILDLINK_ORDER is handled by a single new
variable BUILDLINK_TREE. Each buildlink3.mk file adds a pair of
enter/exit marker, which can be used to reconstruct the tree and
to determine first level includes. Avoiding := for large variables
(BUILDLINK_ORDER) speeds up parse time as += has linear complexity.
The include guard reduces system time by avoiding reading files over and
over again. For complex packages this reduces both %user and %sys time to
half of the former time.
jfranz at bsdprojects dot net.
The binary I/O stream class library presents a platform-independent way to
access binary data streams in C++.
The library is hardware independent in the form that it transparently
converts between the different forms of machine-internal binary data
representation.
It further employs no special I/O protocol and can be used on arbitrary
binary data sources.
