Yikes. int64_t{1}<<31 doesn't actually make sense.

Change-Id: I77a36db6129f2d7f2124181a1b7ea7d9369bc4ac
Reviewed-on: https://code-review.googlesource.com/c/re2/+/58670
Reviewed-by: Paul Wankadia <junyer@google.com>
diff --git a/re2/testing/regexp_benchmark.cc b/re2/testing/regexp_benchmark.cc
index acf6e88..5050286 100644
--- a/re2/testing/regexp_benchmark.cc
+++ b/re2/testing/regexp_benchmark.cc
@@ -949,7 +949,7 @@
   if (prog == NULL) {
     Regexp* re = Regexp::Parse(regexp, Regexp::LikePerl, NULL);
     CHECK(re);
-    prog = re->CompileToProg(int64_t{1}<<31);  // mostly for the DFA
+    prog = re->CompileToProg(int64_t{1}<<30);  // mostly for the DFA
     CHECK(prog);
     cache[regexp] = prog;
     re->Decref();