Two fixes in one:
Firstly, replace non-standard __uint64_t with standard (but optional) uint64_t.
__uint64_t is not a part of C standard; it is defined by some platforms but might not
be present in every environment (e.g. in freestanding build). On the other hand, uint64_t
is standard C. It is optional but virtual guaranteed to be present for any 32/64 bit machine.
Secondly, mark riscv64 for 128-bit long double in make/cmake files. This fixes cmake
build (which detects presence of long double and tries to compile extended functions),
and brings make build to do the same.
Co-authored-by: Viral B. Shah <ViralBShah@users.noreply.github.com>