package/kmsxx: don't install static libraries when BR2_SHARED_STATIC_LIBS=y

package/kmsxx: don't install static libraries when BR2_SHARED_STATIC_LIBS=y

The kmsxx build system can only build either shared libraries *or*
static libraries, not both. Therefore, the build currently fails when
BR2_SHARED_STATIC_LIBS=y because we try to install the static
libraries, that haven't been built.

We fix this by not installing the static libraries when
BR2_SHARED_STATIC_LIBS=y, making BR2_SHARED_STATIC_LIBS=y essentially
the same as BR2_SHARED_LIBS=y for this package.

Fixes bug #10331.

Reported-by:  Frederic MATHIEU <frederic.mathieu@dualis.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>