Log message:
Simply and speed up buildlink3.mk files and processing.
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.

Log message:
Explicitly disable wxGTK support.

Log message:
supports user-destdir

Log message:
Import gpac version 0.4.5.

GPAC features encoders and multiplexers, publishing and content distribution
tools for MP4 and 3GPP or 3GPP2 files and many tools for scene descriptions
(BIFS/VRML/X3D converters, SWF/BIFS, SVG/BIFS, etc...). MP4Box provides all
these tools in a single command-line application.