brltty builds host tools which rely on the expat library, and
pkg-config is used to detect the expat library.
Since commit cd16e18584 ("pkgconf:
always keep system libs"), the wrapper script added
--keep-system-libs, which adds a -L$(STAGING_DIR)/usr/lib to the
pkg-config results instead of just -lexpat. So, previously, by chance,
the pkg-config result for the target expat was "good enough" for the
host expat as well. But now that -L$(STAGING_DIR)/usr/lib is added, it
breaks the build in all sort of ways as obviously building host
binaries with the library search path pointing to $(STAGING_DIR) is
not a good idea.
To fix that, this commit adjusts the brltty build system so that the
PKG_CONFIG_FOR_BUILD variable is used when using pkg-config to build
host binaries.
Fixes:
http://autobuild.buildroot.net/results/5a64dfb845389882c366b6c91aaf5868c090a802/
Many thanks to the initial work from Fabrice Fontaine at
http://patchwork.ozlabs.org/patch/1238163/ which provided an initial
starting point for this investigation.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
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