Create a soong module for ndk_system STL headers

This STL does not have a prebuilt, but does provide headers for
compilation. Soong adds -isystem
prebuilts/ndk/current/sources/cxx-stl/system/include to the compile path
for modules that have stl = "ndk_system"

Bazel poses stricter sandboxing constraints. In preparation for
building sdk variants with Bazel, create a Soong module that explicitly
specifies the .h files contributed by this STL (via

This will be a no-op in Soong.

Test: m nothing
Bug: 298258442
Change-Id: If40b644fdaf23dc99a563a7265e9e4b38f8626ef
1 file changed