gmp: also generate the libgmpcxx library & package it properly
configure runs few checks to make sure c++ compiler and runtime are working
as expected with the --enable-cxx=detect option. And it enables building
of libgmpxx library.
Same as earlier the libgmp.so.10.x file is packaged in the libgmp10 package,
and a new package named libgmpxx4 is added for libgmpxx.so.4.x file.
Signed-off-by: Nitin A Kamble <nitin.a.kamble@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
