build: Fix libraw definitions (again)

[lgritz]

Fixes #4586
Replaces #4587

[lgritz]

@OgreTransporter

[OgreTransporter]

This is not necessary in this way. If the definitions are added via COMPILE_OPTIONS, -D must be specified because target_compile_options is used in the background which adds pure compiler commands. If the definitions are added via DEFINITIONS, -D does not have to be specified because target_compile_definitions is used in the background, which automatically adds -D if necessary.

[lgritz]

Oh, I see now. The libraw definitions aren't really just "definitions" (in the preprocessor symbol sense), they may have compiler flags mixed in.

[lgritz]

Amended the PR.

[OgreTransporter]

The libraw definitions aren't really just "definitions" (in the preprocessor symbol sense), they may have compiler flags mixed in.

This depends on the platform and the compiler. In my MSVC version of libraw, no flags are set in the package, but this can be different depending on the build options.

The PR should fix that problem. Thanks!

[lgritz]

Yeah, it's obviously rare. I'm not actually sure what combination of factors makes it have any extra compile flags, but it obviously did for somebody to prompt the PR that started all this.