Test that all desktop GLSL versions can be cross-linked.

Verified using the NVIDIA proprietary driver for Linux (version
313.18).

Reviewed-by: Eric Anholt <eric@anholt.net>
summary.py: Fix empty generation of problems, changes, etc

The list comprehension can be further refined to be fixed, but the
resulting code is much more difficult to read than the try/except
statement.

This reverts commit aaae592490a6459aba52bc306b819a7fcbaa3008.
This reverts commit 450935b06f8508d3f4177fe7336e3bdee3973a9e.

CC: Paul Berry <stereotype441@gmail.com>
Signed-off-by: Dylan Baker <baker.dylan.c@gmail.com>
gs: Test that gl_MaxGeometryInputComponents can actually be achieved.
gs: Fix geometry layout case insensitivity tests.

These tests use check_link: true, which means that they each need to
specify a complete set of geometry shader layout qualifiers in order
to pass.
gs: Test redeclaring either gl_PerVertex in or out, and using both.
Test a corner case involving arrays, structs, and interface blocks.

This patch exercises the same corner case as
https://bugs.freedesktop.org/show_bug.cgi?id=70368.