- Put 'my_getpagesize' in it's own .c file
 - Map the call 'my_getpagesize' directly to 'getpagesize' if it exists
 - Add default implementation for 'my_getpagesize' to be used if no platform
   specfic function exists


include/my_sys.h:
  Break out the defines for my_getpagesize from HAVE_SYS_MMAN_H as they don't depend on that.
  There is a check for the function in configure which defines HAVE_GETPAGESIZE if the function
  exists
mysys/CMakeLists.txt:
  Add new fil my_getpagesize.c
mysys/Makefile.am:
  Add new fil my_getpagesize.c
mysys/my_mmap.c:
  Remove my_getpagesize from my_mmap.c as it's now implemented in my_getpagesize.c
mysys/my_getpagesize.c:
  New BitKeeper file ``mysys/my_getpagesize.c''