include: Replace hexadecimal representation of four character codes in WINED3DFORMAT enum with macros using the actual characters.

This makes some of the problems in there a bit more obvious.

avifil32: Use chunksize specified by the chunk itself, avoids a noticable ticking sound heard when reading past the chunk boundary.

ntdll: Implement LdrQueryImageFileExecutionOptions and use it to retrieve the per-process global flag.