* configure.ac
(gcry_cv_gcc_inline_asm_riscv, gcry_cv_gcc_inline_asm_riscv_v)
(HAVE_GCC_INLINE_ASM_RISCV_V, HAVE_CPU_ARCH_RISCV): Add RISC-V
detection support.
* mpi/config.links: Add setup for RISC-V links.
* src/Makefile.am: Add 'hwf-riscv.c'.
* src/g10lib.h (HWF_RISCV_IMAFDC, HWF_RISCV_V, HWF_RISCV_ZBB)
(HWF_RISCV_ZBC): New.
* src/hwf_common.h (_gcry_hwf_detect_riscv): New.
* src/hwf-riscv.c: New.
* src/hwfeatures.c: Add "riscv-imafdc", "riscv-v", "riscv-zbb",
and "riscv-zbc".