Z3 errors: fix the regexp in driver

drivers/z3.drv

@@ -27,7 +27,7 @@ transformation "encoding_smt"
 outofmemory "(error \".*out of memory\")\\|Cannot allocate memory"
 timeout "interrupted by timeout"
 (* stop reporting Z3 2.19 warnings as errors *)
-fail "^(error \"\\(W\\(A\\(R\\(N\\(I\\(N[^G]\\|[^N]\\)\\|[^I]\\)\\|[^N]\\)\\|[^R]\\)\\|[^A]\\)\\|[^W]\\)\\(.*\\)\")" "Error: \1"
+fail "^(error \"\\(\\(W\\(A\\(R\\(N\\(I\\(N[^G]\\|[^N]\\)\\|[^I]\\)\\|[^N]\\)\\|[^R]\\)\\|[^A]\\)\\|[^W]\\).*\\)\")" "Error: \\1"
 
 
 (** Extra theories supported by Z3 *)