Deprecate ARM FPA in GDB

Hi,
I plan to deprecate and remove ARM FPA support in GDB 8.1.  The GCC FPA
deprecation discussion was started in 2010 in
https://gcc.gnu.org/ml/gcc/2010-05/msg00442.html and it was removed
in 2012 https://gcc.gnu.org/ml/gcc-patches/2012-06/msg00825.html

The deprecation means GDB no longer has options "fpa" and "softfpa" in
command "set arm fpu".  Currently, it is,

(gdb) set arm fpu
auto     fpa      softfpa  softvfp  vfp

--=20
Yao (=E9=BD=90=E5=B0=A7)