Bug 627993 - Inconsistent storage of password expiry times

Commit made in 5727b8899700f574026bc9be5a1990c4c66619cf introduced
a bug.  The commit removed 2 functions format_genTime and
parse_genTime from slapi-private.h.  But they are used in plugins,
which requires them in the header file.  This fix restores the
function declarations.

ldap/servers/slapd/slapi-private.h

@@ -1117,8 +1117,10 @@ time_t read_localTime(struct berval* from);
 time_t parse_localTime(char* from);
 void write_localTime(time_t from, struct berval* into);
 time_t current_time( void );
+char* format_genTime(time_t from);
 void write_genTime(time_t from, struct berval* into);
 time_t read_genTime(struct berval* from);
+time_t parse_genTime(char* from);
 long parse_duration(char *value);
 char *gen_duration(long duration);