MFC r308006: libunwind: consistently add \n to log and trace messages

Previously most messages included a newline in the string, but a few of
them were missing. Fix these and simplify by just adding the newline in
the _LIBUNWIND_LOG macro itself.

While here correct 'libuwind' typo (missing 'n').

Upstream LLVM libunwind commits r280086 and r280103.

Sponsored by: The FreeBSD Foundation