[libpng17] Imported from libpng-1.7.0beta32.tar
[libpng17] Bump version to 1.7.0beta33
[libpng17] Fixed typos in the manual and in scripts/pnglibconf.dfa

(CFLAGS -> CPPFLAGS and PNG_USR_CONFIG -> PNG_USER_CONFIG).
[libpng17] Imported from libpng-1.7.0beta33.tar
[libpng17] Bump version to 1.7.0beta34
[libpng17] Treat CRC error handling with png_set_crc_action(), instead of with

png_set_benign_errors(), which has been the case since libpng-1.6.0beta18.