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.

Contrary to the MSDN, you can 'create only' whilst using a previous value
(ie +-variable and [~];value). This breaks the install of an application
I was debugging who uses that throughout for all their variables. In
addition whilst adding some tests I've also cleaned up invalid prefix
syntax handling and semicolon removal if the original string is empty.