xfsprogs: fix shared-only build

The shared-only build is not supported by xfsprogs because without
--enable-static, the builtin libraries (libxfs, libxcmd ...)  are only
built as shared libraries and xfs tools requires the static ones.

Also, we needs to replace -static with -static-libtool-libs for the
shared-only case, in order to fallback to linking with the shared
version of libuuid library.

Fixes:
http://autobuild.buildroot.net/results/139/139fa30756d35a24209136068c818802074908de/
http://autobuild.buildroot.net/results/e2e/e2eef5dbadec555756a912a24978c78c0013ee70/
http://autobuild.buildroot.net/results/08c/08c4bc5037379a8ca312e3e7574067235da74030/



And many more.

[Thomas: fix misc typos in the patch description and commit title.]

Signed-off-by: Romain Naour <romain.naour@openwide.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>