Fix matchbox build
This patch fixes various failures in the Matchbox build:
* libmatchbox and matchbox-panel were using a now legacy index()
function, which is not part of every uClibc build nowadays
(depending on the configuration). As this function doesn't exist
anymore in all builds, use strchr() instead, which is the
recommended replacement for index(). Two patches, one for
libmatchbox, one for matchbox-panel, are added to fix this problem.
Closes bug http://bugs.uclibc.org/view.php?id=5484
* Do not override the CFLAGS and LDFLAGS values, they are already set
by TARGET_CONFIGURE_OPTS. It caused build failures.
* Mangle the library paths in the .la file of libmatchbox, after
installation in the staging dir.
It would probably be nice to switch Matchbox over to the new
Makefile.autotools.in.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>