In preparation for RISC-V/Linux `gdbserver' support factor out parts of
native target description determination code that can be shared between
the programs.
gdb/
* nat/riscv-linux-tdesc.h: New file.
* nat/riscv-linux-tdesc.c: New file, taking code from...
* riscv-linux-nat.c (riscv_linux_nat_target::read_description):
... here.
* configure.nat <linux> <riscv*>: Add nat/riscv-linux-tdesc.o to
NATDEPFILES.
f6480e7000