Enchanced my_once..() functions.

Cleaned up charset.c
Removed non fatal memory leak in charset.c

include/my_sys.h

@@ -505,6 +505,8 @@ extern int my_setwd(const char *dir,myf MyFlags);
 extern int my_lock(File fd,int op,my_off_t start, my_off_t length,myf MyFlags);
 extern gptr my_once_alloc(uint Size,myf MyFlags);
 extern void my_once_free(void);
+extern char *my_once_strdup(const char *src,myf myflags);
+extern char *my_once_memdup(const char *src, uint len, myf myflags);
 extern my_string my_tempnam(const char *dir,const char *pfx,myf MyFlags);
 extern File my_open(const char *FileName,int Flags,myf MyFlags);
 extern File my_register_filename(File fd, const char *FileName,

mysys/my_once.c

@@ -78,6 +78,25 @@ gptr my_once_alloc(unsigned int Size, myf MyFlags)
 } /* my_once_alloc */
 
 
+char *my_once_strdup(const char *src,myf myflags)
+{
+  uint len=strlen(src)+1;
+  char *dst=my_once_alloc(len, myflags);
+  if (dst)
+    memcpy(dst, src, len);
+  return dst;
+}
+
+
+char *my_once_memdup(const char *src, uint len, myf myflags)
+{
+  char *dst=my_once_alloc(len, myflags);
+  if (dst)
+    memcpy(dst, src, len);
+  return dst;
+}
+
+
 /*
   Deallocate everything used by my_once_alloc