Added missing space in SQLite LPM fuzzer

This missing space may have screwed up WHERE statements when creating
indexes (or might not have, since I don't see any errors. Adding anyway)

R=metzman@chromium.org, pwnall@chromium.org

Bug: 909886
Change-Id: Idd322f43a2b715d1d282546df4c504148a5014a4
Reviewed-on: https://chromium-review.googlesource.com/c/1387837
Commit-Queue: Victor Costan <pwnall@chromium.org>
Reviewed-by: Jonathan Metzman <metzman@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#618376}

third_party/sqlite/fuzz/sql_query_proto_to_string.cc

@@ -2271,8 +2271,10 @@ CONV_FN(CreateIndex, ci) {
   ret += "(";
   ret += IndexedColumnListToString(ci.icol_list());
   ret += ")";
-  if (ci.has_where())
+  if (ci.has_where()) {
+    ret += " ";
     ret += WhereStatementToString(ci.where());
+  }
   return ret;
 }