CBMC: Speed up proof of polyvec_matrix_expand

Signed-off-by: Rod Chapman <rodchap@amazon.com>

Author: rod-chapman

proofs/cbmc/polyvec_matrix_expand/Makefile

@@ -26,7 +26,8 @@ USE_DYNAMIC_FRAMES=1
 
 # Disable any setting of EXTERNAL_SAT_SOLVER, and choose SMT backend instead
 EXTERNAL_SAT_SOLVER=
-CBMCFLAGS=--smt2 --arrays-uf-always --slice-formula
+CBMCFLAGS=--external-smt2-solver $(PROOF_ROOT)/lib/z3_no_bv_extract --z3
+CBMCFLAGS += --slice-formula
 
 FUNCTION_NAME = polyvec_matrix_expand