MINOR: standard: add 64 bits conversion functions

This patch adds 3 functions for 64 bit integer conversion.

 * lltoa_r : converts signed 64 bit integer to string
 * read_uint64 : converts from string to signed 64 bits integer with capping
 * read_int64 : converts from string to unsigned 64 bits integer with capping
diff --git a/include/common/standard.h b/include/common/standard.h
index ec56654..085ec79 100644
--- a/include/common/standard.h
+++ b/include/common/standard.h
@@ -105,6 +105,7 @@
  */
 extern char itoa_str[][171];
 extern char *ultoa_r(unsigned long n, char *buffer, int size);
+extern char *lltoa_r(long long int n, char *buffer, int size);
 extern char *sltoa_r(long n, char *buffer, int size);
 extern const char *ulltoh_r(unsigned long long n, char *buffer, int size);
 static inline const char *ultoa(unsigned long n)
@@ -495,6 +496,9 @@
 	return i;
 }
 
+unsigned long long int read_uint64(const char **s, const char *end);
+long long int read_int64(const char **s, const char *end);
+
 extern unsigned int str2ui(const char *s);
 extern unsigned int str2uic(const char *s);
 extern unsigned int strl2ui(const char *s, int len);