glsl/glcpp: Add explicit error for "#define without macro name"

glsl/glcpp: Add explicit error for "#define without macro name"

Previously, glcpp would emit an error like this if <EOF> happened to occur
immediately after the "#define", but in general would just get confused,
(leading to un-helpful error messages).

To fix things to generate a clean error message, we do a few things:

	1. Don't require horizontal whitespace immediately after #define

	2. Add a production for the error case, (DEFINE_TOKEN followed
	   immediately by a NEWLINE token).

	3. Make the lexer reset to the <INITIAL> state after every NEWLINE.

This 3rd point prevents the lexer from getting so confused and generating
further spurious errors in the file because it was stuck in the <DEFINE> start
condition.

We also drop the similar error message from the <EOF> rule since the
newly-added rule will have already printed the error message.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>