glsl-1.50: Test compilation of interface blocks containing unsized arrays.

Although it's not explicitly stated in the GLSL 1.50 spec, unsized
arrays are allowed in interface blocks.

section 1.2.3 (Changes from revision 5 of version 1.5) of the GLSL
1.50 spec says:

    * add unsized arrays for block members

And section 7.1 (Vertex and Geometry Shader Special Variables)
includes an unsized array in the built-in gl_PerVertex interface
block:

    out gl_PerVertex {
        vec4 gl_Position;
        float gl_PointSize;
        float gl_ClipDistance[];
    };

Furthermore, GLSL 4.30 contains an example of an unsized array
occurring inside an interface block.  From section 4.3.9 (Interface
Blocks):

    uniform Transform {  // API uses "Transform[2]" to refer to instance 2
        mat4           ModelViewMatrix;
        mat4           ModelViewProjectionMatrix;
        vec4           a[];  // array will get implicitly sized
        float          Deformation;
    } transforms[4];

This patch adds compiler tests to verify that in and out blocks can
contain unsized arrays.

Verified using the NVIDIA proprietary driver for Linux.