package/libuwsc: fix wolfssl build

libuwsc needs BR2_PACKAGE_WOLFSSL_ALL (which enables openssl compat
layer) to avoid the following wolfssl build failure raised since the
addition of the package in commit
120c0477:

/home/br-user/work/instance-1/output-1/build/libuwsc-3.3.5/src/ssl.c:62:5: error: unknown type name 'SSL_CTX'
   62 |     SSL_CTX *ctx;
      |     ^~~~~~~

Note that we do not select _ALL when wolfssl is enabled, because wolfssl
is neither the only nor the preferred choice, so the condition would
have to be a bit more complex:

    select BR2_PACKAGE_WOLFSSL_ALL if BR2_PACKAGE_WOLFSSL \
        && !BR2_STATIC_LIBS && !BR2_PACKAGE_OPENSSL

It is not overly complicated, but it is no longer trivial or obvious,
and would easily break if the ordering of preferences were to change in
the .mk fie in the future.

Fixes:
 - http://autobuild.buildroot.org/results/6c2a6ed6fca1f92aab299f6ed9cd900b20e8d512



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
[yann.morin.1998@free.fr: explain why we don't select _ALL]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>