glsl: non-last member unsized array on SSBO must fail compilation on GLSL ES 3.1

glsl: non-last member unsized array on SSBO must fail compilation on GLSL ES 3.1

From GLSL ES 3.10 spec, section 4.1.9 "Arrays":

"If an array is declared as the last member of a shader storage block
 and the size is not specified at compile-time, it is sized at run-time.
 In all other cases, arrays are sized only at compile-time."

In desktop GLSL it is allowed to have unsized-arrays that are
not last, as long as we can determine that they are implicitly
sized, which is detected at link-time.

With this patch Mesa reports a compilation error as glslang does with
the following shader:

buffer SSBO { vec4 data[]; vec4 moreData;};
void main (void)
{
}

Fixes:
dEQP-GLES31.functional.debug.negative_coverage.log.shader.compile_compute_shader
dEQP-GLES31.functional.debug.negative_coverage.callbacks.shader.compile_compute_shader
dEQP-GLES31.functional.debug.negative_coverage.get_error.shader.compile_compute_shader

Cc: "17.0" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Jose Maria Casanova Crespo <jmcasanova@igalia.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>