src.libnames.mk: NEED/WANT_COMPAT+static support

Look in _LIB_OBJTOP for all static libraries not just INTERNALLIBs. In
normal operation this is a no-op, but improves the consistency of this
file.

Reviewed by: imp, jhb
Obtained from: CheriBSD
Differential Revision: https://reviews.freebsd.org/D35822