Export _libc_arm_fpu_present as a private symbol to be used by other
system libraries, for example libm.
MFV r262983:

4638 Panic in ZFS via rfs3_setattr()/rfs3_write(): dirtying snapshot!

illumos/illumos-gate@2144b121c08e0eb676cc6ca4662ebbc9f9c22fe3
Correct a typo in nlm_find_host_by_addr(): the intention of the
code is to give "<unknown>" rather than comparing the buffer
against it.

MFC after:	2 weeks