[smart][risc-v/libcpu] port rv64 cpu code (#6704)

* [risc-v/libcpu] porting Smart & RTOS
* [fix] rv64 plic
* [risc-v/rv64] remove macro in rtdef

components/lwp/arch/risc-v/rv64/lwp_arch.h

@@ -50,6 +50,7 @@ extern "C" {
 #endif
 
 rt_mmu_info* arch_kernel_get_mmu_info(void);
+int arch_expand_user_stack(void *addr);
 
 rt_inline unsigned long rt_hw_ffz(unsigned long x)
 {

components/lwp/lwp.c

@@ -1320,7 +1320,7 @@ pid_t lwp_execve(char *filename, int debug, int argc, char **argv, char **envp)
 #ifdef RT_USING_MUSL
 extern char **__environ;
 #else
-char __environ = 0;
+char **__environ = 0;
 #endif
 
 pid_t exec(char *filename, int debug, int argc, char **argv)