Rewrite LDLIBS and SHARED_LIBRARIES

LOCAL_LDLIBS was the only correct way to use NDK libraries, but few used
it correctly. It also often got confused with LOCAL_LDFLAGS, so move the
flags to the correct variable.

For binaries that weren't using the NDK (empty LOCAL_SDK_VERSION), it
was never valid to use LOCAL_LDLIBS, as dependencies would not be
properly set up, and could lead to random build failures. So convert any
-l linker flags to using LOCAL_SHARED_LIBRARIES automatically.

For binaries built using the NDK (LOCAL_SDK_VERSION set), they were
required to use LOCAL_LDLIBS for prebuilt NDK libraries, otherwise they
would get headers and dependencies to the platform versions. Any
non-prebuilt LOCAL_LDLIBS would miss dependencies. So move the NDK
prebuilt libraries to LDLIBS from SHARED_LIBRARIES, and move everything
else to SHARED_LIBRARIES.

So now, for device modules, LOCAL_SHARED_LIBRARIES should always be
used, and we'll do the right thing. LOCAL_LDLIBS should only be used for
host libraries from the system.

Change-Id: Ide34c7afdcfb6507a378d45a42471729e489a9e0