Test that the fs gl_PrimitiveID input works even when there's no gs.

For i965/gen7 hardware, the driver has to go to extra work to make
gl_PrimitiveID work in the case where there is no geometry shader.  So
we need a separate test to make sure that works properly.

Reviewed-by: Eric Anholt <eric@anholt.net>
Test interpolation qualifiers inside of interface blocks.

Validated using the NVIDIA proprietary driver for Linux (version
313.18).
Test the "centroid" qualifier inside of interface blocks.

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