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.
While here, add DESTDIR support.
1.2.6
* Fix an infinite loop regression from 1.2.3
* Fix possible noise at the beginning of files
1.2.5
* Properly increase API version since it has changed since 1.2.3
Apps compiled with 1.2.2 WILL BREAK when used with 1.2.3 & 1.2.4 libs installed
