Update devel/libbson to 1.1.2.

Libbson 1.1.2
=============
* sscanf_s doesn't exist for mingw.

Libbson 1.1.0
=============
ABI/API changes include:
* Deprecation of bson_copy_to_excluding
* Addition of bson_copy_to_excluding_noinit
* Removal of MIN, MAX and ABS macros in favor of BSON_MIN, BSON_MAX and
  BSON_ABS.  Note this is a breaking source level change if you relied on
  these from bson.h.  Also note that this is not a breaking ABI change.
* Addition of BSON_ERROR_BUFFER_SIZE macro

Other changes include:
* Addition of a versioned ABI for the libbson shared library
* fixed bson_get_monotonic_time fallback when a system monotonic clock can not
  be found.  Formerly failed to compile with an incorrect call to
  bson_gettimeofday
* Allow the "dbref" convention in bson_validate when BSON_VALIDATE_DOLLAR_KEYS
  is present
* Support for ISO-8601 or $numberLong dates in bson <-> json parsing
* Quiet various compiler warnings

(fhajny)