Enable _LIBCPP_DEBUG=0 on Android too

This was left disabled on Android due to a couple of bugs. Now that
https://chromium-review.googlesource.com/c/chromium/src/+/1924235 and
https://chromium-review.googlesource.com/c/chromium/src/+/1958608 are
in, enable it on Android too.

Bug: 923166
Change-Id: Ida85ea7eb84e1c4d6e90d321ab5344e1370fdfe8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1958806
Auto-Submit: David Benjamin <davidben@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#723159}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 3dd591611afed0c72749c373442da95492cbf3cb

config/c++/BUILD.gn

@@ -63,11 +63,7 @@ config("runtime_library") {
   # The Windows component build fails to link with libc++'s debug mode. See
   # https://crbug.com/923166#c33, https://crbug.com/923166#c44, and
   # https://llvm.org/PR41018.
-  #
-  # Some Android tests fail with _LIBCPP_DEBUG=0 due to bugs. See
-  # https://crbug.com/923166#c43 and https://crbug.com/923166#c47. Once those
-  # fixes land, this should also be enabled on Android.
-  if (!(is_win && is_component_build) && !is_android) {
+  if (!(is_win && is_component_build)) {
     # libc++ has two levels of debug mode. Setting _LIBCPP_DEBUG to zero
     # enables most assertions. Setting it to one additionally enables iterator
     # debugging. See https://libcxx.llvm.org/docs/DesignDocs/DebugMode.html