Disable error due to warning on iOS.

The explicit warning is benign on iOS but this TU is compiled with warnings as
errors. Explicitly disable the warning in the one sqlite3 TU on iOS.

Change-Id: Iea4974cf9f53373b7c57cfacc06d76f82416cca6
Reviewed-on: https://flutter-review.googlesource.com/c/third_party/sqlite/+/24221
Reviewed-by: Zach Anderson <zra@google.com>
Commit-Queue: Chinmay Garde <chinmaygarde@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index f62b4d5..e991f7f 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -31,5 +31,9 @@
     "SQLITE_OMIT_AUTOINIT=1",
   ]
 
+  if (is_ios) {
+    defines += [ "HAVE_GETHOSTUUID=0" ]
+  }
+
   sources = [ "sqlite3.c" ]
 }