This patch removes:
- CHECK_SYMBOL_EXISTS(getpagesize "unistd.h" HAVE_GETPAGESIZE)
  This check passes on all non-Windows supported platforms. On Windows we 
  use a replacement implementation.
- CHECK_SYMBOL_EXISTS(finite  "math.h" HAVE_FINITE_IN_MATH_H)
  This check passes on all supported platforms.
  Note that on Windows we replace finite by _finite.
- #ifdef HAVE_UNIDATA
  Always set.
- #ifdef UNICODE_32BIT, USE_INTERNAL_CTYPE, USE_ISO_8859_1, SET_INEXACT,
  WANT_OUR_ATOI, INVERT_TERTIARY_WEIGHTS, DEC_MULTINATIONAL_CHAR,
  HP_MULTINATIONAL_CHAR
  Never set.
- hash_filo.cc
  This file is empty.

The patch also changes (to fix linking warnings):
- vio/CMakeLists.txt so that viopipe.c and vioshm.c are only compiled on Windows.
- zlib/CMakeLists.txt so that header files are not listed as source files.
- sql/CMakeLists.txt so that des_key_file.cc and mf_iocache.cc are not compiled
  for embedded server.