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.
The LIBMAA library provides many low-level data structures which are
helpful for writing compilers, including hash tables, sets, lists,
debugging support, and memory management. Although LIBMAA was
designed and implemented as a foundation for the Khepera
Transformation System, the data structures are generally applicable to
a wide range of programming problems.
The memory management routines are especially helpful for improving the
performance of memory-intensive applications.
