'#pragma include' error on Intel HD graphics card

[Mikhail]

Intel HD GLSL compiler tries to parse the '#pragma include' statement:

> :display:gsg:glgsg(error): An error occurred while compiling GLSL compute shader grain.compute.glsl:
> ERROR: grain.compute.glsl:10: '' : illegal character (") (0x22)
> ERROR: grain.compute.glsl:10: '' : #pragma directive must end with a newline

As soon as it has already preprocessed by Panda3D, there no need to keep it in shader source.

Bug was originally discovered here: https://github.com/tobspr/RenderPipeline/issues/48

[rdb (rdb)]

Thanks, I've committed a fix.