neuralnetworks namespace links to system namespace in [vendor] section

This change fixes a bug that neuralnetworks namespace is linked to the
default namespace in [vendor] section. Default namespace is for
/vendor/lib in [vendor] section. System libraries are available in the
'system' namespace.

Bug: 139113342
Test: N/A
Change-Id: I1b6751e5e33522f9829f3d9ad7371efdce01b0f0