package/lapack: avoid selecting lapack and clapack

package/lapack: avoid selecting lapack and clapack

lapack and clapack generate the same libraries liblapack.so and
libblas.so. So those two packages can't be selected at the same time.

This is a temporary fix waiting for a solution[2].

So:
- add !BR2_PACKAGE_CLAPACK to lapack/Config.in.

[1]: http://autobuild.buildroot.org/results/375/375078ed8f965ecf92eb9674bd071a518c3ef894//
[2]: http://lists.busybox.net/pipermail/buildroot/2019-August/255894.html

Signed-off-by: Alexandre PAYEN <alexandre.payen@smile.fr>
Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Cc: Romain Naour <romain.naour@smile.fr>
Cc: Thomas De Schampheleire <patrickdepinguin@gmail.com>
Reviewed-by: Romain Naour <romain.naour@smile.fr>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>