Always call into native loader when load a native library

Namespace has been enabled at native bridge side. And, native loader
wraps both dynamic linker and native bridge now. Frameworks on longer
call native bridge directly when it load a native library, but still
remember whether native bridge is needed for each library.

Bug: http://b/28242460


Change-Id: I6b25e0621168cea0885c890c544b355a68309fa7
Signed-off-by: Zhenhua WANG <zhenhua.wang@intel.com>