pointer-based newlib implementation.
(_ctype_b): Declare.
(__ctype_cp): Move to newlib. Declare.
(__ctype_iso): Ditto.
(__set_ctype): Implement changing __ctype_ptr__. Only copy character
class data in applications built under older Cygwin.
* cygwin.din (__ctype_ptr__): Export.
* include/ctype.h: Remove in favor of newlib implementation.
* include/cygwin/config.h (__EXPORT): Define alongside __IMPORT.
* include/cygwin/version.h (CYGWIN_VERSION_CHECK_FOR_OLD_CTYPE):
Define check for old vs. new ctype implementation.
Bump API minor number.