Sets wasm_worning_as_error disabled by default. (#1406)

This removes `-Werror` set by default, thus conforming with default
bazel cc toolchain.

Co-authored-by: William Izzo <william.izzo@hey.com>

Author: WilliamIzzo83

bazel/emscripten_toolchain/toolchain.bzl

@@ -445,7 +445,7 @@ def _impl(ctx):
         ),
         feature(
             name = "wasm_warnings_as_errors",
-            enabled = True,
+            enabled = False,
         ),
 
         # ASan and UBSan. See also: