net/gupnp-igd: fix build with GCC-based architectures

Add USES=compiler:c11 to fix build:
/usr/local/include/gupnp-1.2/libgupnp/gupnp-acl.h:39: error: redefinition of typedef 'GUPnPAcl'
/usr/local/include/gupnp-1.2/libgupnp/gupnp-acl.h:32: error: previous declaration of 'GUPnPAcl' was here
/usr/local/include/gupnp-1.2/libgupnp/gupnp-acl.h:53: error: redefinition of typedef 'GUPnPAclInterface'
/usr/local/include/gupnp-1.2/libgupnp/gupnp-acl.h:32: error: previous declaration of 'GUPnPAclInterface' was here

Approved by: mentors (implicit approval)