These generators create two kinds of tests.  The first verifies that
pre- and post-increment/decrement operations cannot be assignment
targets.  These look like:

uniform float u;
varying vec4 v;

void main()
{
    float t = u;

    ++t = float(v.x);
    gl_FragColor = vec4(t, v.yzw);
}

The second kind of test verifies that pre- and
post-increment/decrement operations cannot be used for function 'out'
parameters.  These look like:

uniform ivec4 u;
attribute vec4 v;

void f(out ivec4 p)
{
    p = ivec4(v);
}

void main()
{
    ivec4 t = u;

    f(t--);
    gl_Position = vec4(t);
}

Function 'inout' parameters are not explicitly tested.

A test is generated for both vertex and fragment targets for each
int and float vector or scalar datatype.  Matrix types and GLSL 1.30
unsigned types are not tested.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Paul Berry <stereotype441@gmail.com>