* child_info.h: Add _PROC_WHOOPS enum value.

* child_info.h: Add _PROC_WHOOPS enum value.
(CURR_CHILD_INFO_MAGIC): Update.
(child_info::magic): Make 'long'.
* cygheap.h: Export _cygheap_start.
* cygheap.cc: Don't declare _cygheap_start.
* cygmagic: Use cksum to produce checksums.  Append 'U' to end of checksum.
* dcrt0.cc (initial_env): Calculate sleep ms before reusing buffer.
(_dll_crt0): Detect cygheap mismatch as indicative of different cygwin version.
Set child_proc_info to NULL when _PROC_WHOOPS.
(multiple_cygwin_problem): If child_info specific problem, then set
child_proc_info type to _PROC_WHOOPS.
* shared_info.h (CURR_MOUNT_MAGIC): Update.
(CURR_SHARED_MAGIC): Ditto.