qwt-e: exclude from world

* qwt and qwt-e cannot be built in the same sysroot, it's correctly checked:
  | Project ERROR: local build will conflict with /OE/jansa-test/shr-core/tmp-eglibc/sysroots/qemuarm/usr/lib/libqwt.*
  but there is no point to include both in world build

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>