Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add a TestFloat based test suite for floating-point implementations
currently supporting sparc64. After a `make depend all` there are
three programs; testsoftfloat for testing against the SoftFloat in
src/lib/libc/softfloat for reference purposes, testemufloat for
testing the emulator source in src/lib/libc/sparc64/fpu and testfloat
for testing with the installed libc. Support for other architectures
can be added as needed.

PR: 144900
Submitted by: Peter Jeremy

Move TestFloat 2a to the dist subdirectory.

Remove the keywords property.

Initial import of TestFloat 2a.

Obtained from: http://www.jhauser.us/arithmetic/TestFloat.html