[klibc] add rt_sscanf

cherry-pick from: https://github.com/PetteriAimonen/Baselibc/blob/master/src/vsscanf.c

BSD license

Author: mysterywolf

include/klibc/kerrno.h

@@ -12,6 +12,7 @@
 #define __RT_KERRNO_H__
 
 #include <rtconfig.h>
+#include <rttypes.h>
 
 #ifdef __cplusplus
 extern "C" {

include/klibc/kstdio.h

@@ -11,6 +11,9 @@
 #ifndef __RT_KSTDIO_H__
 #define __RT_KSTDIO_H__
 
+#include <rttypes.h>
+#include <stdarg.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -19,6 +22,8 @@ int rt_vsprintf(char *dest, const char *format, va_list arg_ptr);
 int rt_vsnprintf(char *buf, rt_size_t size, const char *fmt, va_list args);
 int rt_sprintf(char *buf, const char *format, ...);
 int rt_snprintf(char *buf, rt_size_t size, const char *format, ...);
+int rt_sscanf(const char *str, const char *format, ...);
+int rt_vsscanf(const char *buffer, const char *format, va_list ap);
 
 #ifdef __cplusplus
 }

include/klibc/kstring.h

@@ -11,6 +11,8 @@
 #ifndef __RT_KSTRING_H__
 #define __RT_KSTRING_H__
 
+#include <rttypes.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -19,6 +21,7 @@ void *rt_memset(void *src, int c, rt_ubase_t n);
 void *rt_memcpy(void *dest, const void *src, rt_ubase_t n);
 void *rt_memmove(void *dest, const void *src, rt_size_t n);
 rt_int32_t rt_memcmp(const void *cs, const void *ct, rt_size_t count);
+
 char *rt_strdup(const char *s);
 rt_size_t rt_strnlen(const char *s, rt_ubase_t maxlen);
 char *rt_strstr(const char *str1, const char *str2);