Some fixes to compile with SS12

** file os/os0file.c : missing #include "trx0trx.h"    
    
** file buf/buf0buf.c: same    
    
** file buf/buf0rea.c: missing #include "srv0srv.h"    
    
** file sql/sql_class.h:    
    
#ifdef __cplusplus    
__BEGIN_DECLS    
#endif    
extern ulonglong frequency;    
#ifdef __cplusplus    
__END_DECLS    
#endif    
    
Don't know why it doesn't like it... (GCC3 also was unhappy here)    
Replaced by:    
    
extern ulonglong frequency;    
    
(seems it never used in C++)    
    
    
** file sql/ha_innodb.cc:      
  line 6736: missing (char *) cast before strchr()    
             p = (char *)strchr( ...    
    
** missing strsep() in Solaris (this function is not POSIX)    
    
Added into sql/sql_show.cc:    
    
char * strsep (char **stringp, const char *delim)    
 {    
  char *start = *stringp;    
  char *ptr;    
    
  if (start == NULL)  return NULL;    
    
  /* Optimize the case of no delimiters.  */    
  if (delim[0] == '\0')    
    {    
      *stringp = NULL;    
      return start;    
    }    
    
  /* Optimize the case of one delimiter.  */    
  if (delim[1] == '\0')    ptr = strchr (start, delim[0]);    
  else    
    /* The general case.  */    
    ptr = strpbrk (start, delim);    
  if (ptr == NULL)    
    {    
      *stringp = NULL;    
      return start;    
    }    
    
  *ptr = '\0';    
  *stringp = ptr + 1;    
    
  return start;    
 }