OpenMP/C++: Avoid ICE for BIND_EXPR with empty BIND_EXPR_BLOCK [PR120413] PR c++/120413 gcc/cp/ChangeLog: * semantics.cc (finish_omp_target_clauses_r): Handle BIND_EXPR with empty BIND_EXPR_BLOCK. gcc/testsuite/ChangeLog: * g++.dg/gomp/target-4.C: New test. (cherry picked from commit 45b849d05b733a25ec7ce612229084b8f4b86d3d)