This prevented expansion of libdir in pkgconfig.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

We should use upstream patch here, which can be removed later,
instead of maintaining our own one.

Reported-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Michael Heimpold <mhei@heimpold.de>

Also remove upstreamed patch.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

musl doesn't support fts. But with the extra package musl-fts installed,
libzip picks up the fts header and fails at the linking stage:

zipcmp.c:(.text.startup+0x130): undefined reference to `fts_open'
/home/sk/tmp/openwrt/staging_dir/toolchain-mips_24kc_gcc-8.3.0_musl/lib/gcc/mips-openwrt-linux-musl/8.3.0/../../../../mips-openwrt-linux-musl/bin/ld: zipcmp.c:(.text.startup+0x172): undefined reference to `fts_read'

So with musl-fts we need to link in libfts. To address that this commits
patches the cmake setup to check if fts is available in libc itself or
in any external libfts.

So when musl-fts is installed on the system the setup will be the
following:

musl: use libfts
uclibc: use fts from libc
glibc: like uclibc

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>