[master] Revised projects to account for new deprecated-stuff detection

  Updated projects/visualc6 and visualc71 with "/d PNG_CONFIGURE_LIBPNG".
    They should work but still need to be updated to remove
    references to pnggccrd.c or pngvcrd.c and ASM building.
  Added README.txt to the beos, cbuilder5, netware, and xcode projects warning
    that they need to be updated, to remove references to pnggccrd.c and
    pngvcrd.c and to depend on pngpriv.h
5 files changed