SDL_CPUPauseInstruction RISCV-64 version proposal.

include/SDL3/SDL_atomic.h

@@ -244,6 +244,8 @@ typedef void (*SDL_KernelMemoryBarrierFunc)();
     #define SDL_CPUPauseInstruction() __asm__ __volatile__("yield" ::: "memory")
 #elif (defined(__powerpc__) || defined(__powerpc64__))
     #define SDL_CPUPauseInstruction() __asm__ __volatile__("or 27,27,27");
+#elif (defined(__riscv) && __riscv_xlen == 64)
+    #define SDL_CPUPauseInstruction() __asm__ __volatile__(".insn i 0x0F, 0, x0, x0, 0x010");
 #elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
     #define SDL_CPUPauseInstruction() _mm_pause()  /* this is actually "rep nop" and not a SIMD instruction. No inline asm in MSVC x86-64! */
 #elif defined(_MSC_VER) && (defined(_M_ARM) || defined(_M_ARM64))