Add support for hardware watchpoints on win32 native.
* win32-nat.c (CONTEXT_DEBUG_DR macro): Add use of
CONTEXT_DEBUG_REGISTERS.
(dr variable): New variable. Static array containing a local copy
of debug registers.
(debug_registers_changed): New variable. Reflects when debug registers
are changed and need to be written to inferior.
(debug_registers_used): New variable. Reflects when any debug register
was set, used when new threads are created.
(cygwin_set_dr, cygwin_set_dr7, cygwin_get_dr6): New functions used by
i386-nat code.
(thread_rec): Set dr array if id is the thread of current_event .
(child_continue, child_resume): Change the debug registers for all
threads if debug_registers_changed.
(child_add_thread): Change the debug registers if debug_registers_used.
* config/i386/cygwin.mh: Add use of i386-nat.o file.
Link nm.h to new nm-cygwin.h file.
+ config/i386/nm-cygwin.h: New file. Contains the macros used for use
of hardware registers.
