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.
libConfuse is a configuration file parser library, licensed under the
terms of the LGPL, and written in C. It supports sections and (lists
of) values (strings, integers, floats, booleans or other sections), as
well as some other features (such as single/double-quoted strings,
environment variable expansion, functions and nested include
statements). It makes it very easy to add configuration file
capability to a program using a simple API.
The goal of libConfuse is not to be the configuration file parser
library with a gazillion of features. Instead, it aims to be easy to
use and quick to integrate with your code. libConfuse was called
libcfg before, but was changed to not confuse with other similar
libraries.
