glcpp: error on multiple #else/#elif directives

The preprocessor currently accepts multiple else/elif-groups
per if-section. The GLSL-preprocessor is defined by the C++
specification, which defines the following parse-rule:

if-section:
	if-group elif-groups(opt) else-group(opt) endif-line

This clearly only allows a single else-group, that has to come
after any elif-groups.

So let's modify the code to follow the specification. Add test
to prevent regressions.

Reviewed-by: Ian Romanick <[email protected]>
Reviewed-by: Kenneth Graunke <[email protected]>
Reviewed-by: Carl Worth <[email protected]>

Cc: 10.0 <[email protected]>

0 files changed, 0 insertions, 0 deletions