target/m68k: implement flognp1

Using a local m68k floatx80_lognp1()
[copied from previous:
Written by Andreas Grabher for Previous, NeXT Computer Emulator.]

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20180305203910.10391-3-laurent@vivier.eu>
6 files changed