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.
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babl is a dynamic, any to any, pixel format translation library.
It allows converting between different methods of storing pixels known
as pixel formats that have with different bitdepths and other data
representations, color models and component permutations.
A vocabulary to formulate new pixel formats from existing primitives is
provided as well as the framework to add new color models and data
types.
