On a x86-64 host, libcap tried to install things in
$(STAGING_DIR)/lib64 and $(TARGET_DIR)/lib64. Therefore, pass lib= and
prefix=, as required by the strange build system used by libcap.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Needed as a dependency of cdrkit, which contains genisomage, useful
for generating ISO9660 filesystem images.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>