[OPENMP51]Initial parsing/sema for adjust_args clause for 'declare variant'

Adds initial parsing and sema for the 'adjust_args' clause.

Note that an AST clause is not created as it instead adds its expressions
to the OMPDeclareVariantAttr.

Differential Revision: https://reviews.llvm.org/D99905

GitOrigin-RevId: fb4c451001d06c600394382e2c6ad6872f78f646
diff --git a/lib/Semantics/check-omp-structure.cpp b/lib/Semantics/check-omp-structure.cpp
index c092499..88f5740 100644
--- a/lib/Semantics/check-omp-structure.cpp
+++ b/lib/Semantics/check-omp-structure.cpp
@@ -1422,6 +1422,7 @@
 CHECK_SIMPLE_CLAUSE(Nocontext, OMPC_nocontext)
 CHECK_SIMPLE_CLAUSE(Filter, OMPC_filter)
 CHECK_SIMPLE_CLAUSE(When, OMPC_when)
+CHECK_SIMPLE_CLAUSE(AdjustArgs, OMPC_adjust_args)
 
 CHECK_REQ_SCALAR_INT_CLAUSE(Grainsize, OMPC_grainsize)
 CHECK_REQ_SCALAR_INT_CLAUSE(NumTasks, OMPC_num_tasks)