drirc: Add quirk to disable GLSL line continuations for Savage2

drirc: Add quirk to disable GLSL line continuations for Savage2

This application is known to contain shaders that:

1. Have a stray backslash as the last line of comment lines
2. Have a declaration immediately following that line

Hence, interpreting that backslash as a line continuation causes the
declaration to be hidden and the shader fails to compile.  Fortunately, the
shaders also:

3. Do not have any other intentional line-continuation characters

So disabling line continuations entirely for the application fixes this
problem without causing any other breakage.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>