Add missing library dependency.

Libcore tests reference standard libcore headers, including objects
that use libnativehelper code. Thus the tests also require
libnativehelper.

This breaks ASan build. Does not reproduce in the normal build because
all libnativehelper references are in dead code, and ASan disables
dead code stripping:
https://code.google.com/p/address-sanitizer/issues/detail?id=260

Bug: 21785137
Change-Id: Ic272384cc1a6f77e81079bf4f4ea751a0ed92ea1
1 file changed