warning: format string is not a string literal (potentially insecure)
[-Wformat-security]

Function open_debug_file_ex() set flag FD_CLOEXEC to opened
file according to the value of third parameter.

Removed duplicity of unsetting FD_CLOEXEC after calling function
open_debug_file_ex()

https://fedorahosted.org/sssd/ticket/1708

The services kept the fd to /var/log/sssd/sssd.log open. I don't think
there's any point in keeping the logfiles open after exec-ing for the
child, so I set the CLOEXEC flag.

https://fedorahosted.org/sssd/ticket/1495

https://fedorahosted.org/sssd/ticket/956

Added: --debug-microseconds=0/1
Added: debug_microseconds to sssd.conf

Removed:
    SSS_UNRESOLVED_DEBUG_LEVEL (completely replaced with SSSDBG_UNRESOLVED)

Added new macro:
    CONVERT_AND_SET_DEBUG_LEVEL(new_value)

Changes unresolved debug level value (SSSDBG_UNRESOLVED) from -1 to 0
so DEBUG macro could be reduced by one condition. Anyway, it has a minor
effect, every time you want to load debug_level from command line parameters,
you have to use following pattern:

    /* Set debug level to invalid value so we can deside if -d 0 was used. */
    debug_level = SSSDBG_INVALID;

    pc = poptGetContext(argv[0], argc, argv, long_options, 0);
    while((opt = poptGetNextOpt(pc)) != -1) { ... }

    CONVERT_AND_SET_DEBUG_LEVEL(debug_level);

https://fedorahosted.org/sssd/ticket/925

Conversion of the old debug_level format to the new one.
(only where it was necessary)

Removed:
  SSS_DEFAULT_DEBUG_LEVEL (completely replaced with SSSDBG_DEFAULT)

https://fedorahosted.org/sssd/ticket/925

Added functions:
- debug_convert_old_level() to convert levels 0-9 to appropriate bitmask
  debug_convert_old_level(5) returns 0x03F0 (= 0 | 1 | 2 | 3 | 4 | 5)

- debug_get_level() to convert old level number to its new value
  debug_get_level(5) returns 0x0200 (= 5)

There are several new macros in util/util.h:

- SSSDBG_* to reflect a debug level (same names as in the ticket) - please,
  don't use magic numbers anymore