Log Message:
Update to GNU Prolog 1.4.4

Changes in GNU Prolog version 1.4.4:

* add Prolog flags c_cc_version_data
* fix a regression bug in linedit
* fix a little bug in the debugger
* add subtract/3 built-in predicate

Changes in GNU Prolog version 1.4.3:

* add new C foreign interface functions converting term to/from C strings
* modify top-level banner to show 32/64 bits, compile date, C compiler name
* modify Linedit: fix Prolog prompt when Linedit is not activated
* modify linedit: accept gui=silent in env var LINEDIT
  (does not warn if the windows gui DLL is not found)
* fixes for Windows 8 (i686 and x86_64) with MSVS 2012, mingw64 gcc > 4.5.3
* add Prolog flags address_bits, compiled_at, c_cc, c_cflags, c_ldflags
* fix a bug in the FD solver (option backtracks in fd_labeling)
* improve the FD solver (better propagation for reified constraints at labeling)
* improve the FD solver (add labeling option: value_method(bisect))
* improve the FD solver (avoid some cases of C stack overflow, improved fd_domain/3)
* fix a bug in the FD solver (regression bug in 1.4.2)
* add PlULong to gprolog.h and PlThrow(ball) to C foreign interface