bswap: add RISC-V support.

Author: pengjunjie2100

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/primitives.h

@@ -101,6 +101,8 @@ inline uint32_t bswap(uint32_t val) {
   __asm__("rev %w[dst], %w[src]" : [dst]"=r"(val) : [src]"r"(val));
 #elif defined(__ppc64__)||(__PPC64__)||(__powerpc64__)||(__loongarch64)
   return  __builtin_bswap32(val);
+#elif #elif defined(__riscv) && __riscv_xlen == 32
+  return  __builtin_bswap32(val);
 #else
   __asm__("bswap %0" : "=r" (val) : "0" (val));
 #endif
@@ -112,6 +114,8 @@ inline uint64_t bswap64(uint64_t val) {
   __asm__("rev %[dst], %[src]" : [dst]"=r"(val) : [src]"r"(val));
 #elif defined(__ppc64__)||(__PPC64__)||(__powerpc64__)||(__loongarch64)
   return __builtin_bswap64(val);
+#elif #elif defined(__riscv) && __riscv_xlen == 64
+  return  __builtin_bswap64(val);
 #else
 #ifdef __X64
   __asm__("bswapq %0" : "=r" (val) : "0" (val));