sqlite: Clean up Android build options.

The default value for SQLITE_DEFAULT_FILE_FORMAT has been 4 for a while.
Besides, the option has a typo in our build file, so it wasn't really
used.

SQLITE_ENABLE_FTS3_BACKWARDS defines fts1 and fts2 as aliases for fts3.
They are not actually used in Chrome.

Change-Id: I1bca922862fcff665e614b098cd17e74f908b60d
Reviewed-on: https://chromium-review.googlesource.com/1146158Reviewed-by: Chris Mumford <cmumford@chromium.org>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577265}

third_party/sqlite/BUILD.gn

@@ -267,8 +267,6 @@ component("chromium_sqlite3") {
       "SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT=1048576",
       "SQLITE_DEFAULT_AUTOVACUUM=1",
       "SQLITE_TEMP_STORE=3",
-      "SQLITE_ENABLE_FTS3_BACKWARDS",
-      "DSQLITE_DEFAULT_FILE_FORMAT=4",
     ]
   }