Make linker_namespaces test run on a device without webview

LinkerNamespacesTest did not take into consideration wear devices
do not support PackageManager.FEATURE_WEBVIEW. This CL fixes this
by adding check this feature.

Bug: http://b/26894351
Change-Id: I28eceeba35b438f2131b8ae20bfa26b310fdcdf3
(cherry picked from commit baae03a7e6b3daa5f390c5448234e80e25ab7ae6)
2 files changed