[PATCH] do not call _dbus_warn_check_failed on checks

[Havoc Pennington]

Oh, to clarify asserts vs. checks. The difference is not whether they 
exit (it is configurable for checks), but what is being sanity-checked. 
checks can appear only on public API and they are supposed to check up 
on data provided by the application (library user). Assertions are 
supposed to check up on libdbus's internal consistency. So while it's 
tough to draw a 100% bright line, in general if an assertion fails we'd 
expect a dbus bug and if a check fails we'd expect an application bug.

This is perhaps most nicely summed up by the assertion at the start of 
the check macros:

#define _dbus_return_if_fail(condition) do { 
          \
    _dbus_assert ((*(const char*)_DBUS_FUNCTION_NAME) != '_'); 
             \
   if (!(condition)) { 
             \
     _dbus_warn_check_failed (_dbus_return_if_fail_warning_format, 
             \
                              _DBUS_FUNCTION_NAME, #condition, __FILE__, 
__LINE__); \
     return; 
             \
   } } while (0)

i.e. there we assert that the check is not used on internal functions 
that start with underscore.

Havoc