glsl: do not allow implicit casts of unsized array initializers

glsl: do not allow implicit casts of unsized array initializers

The GLSL 4.6 specification (section 4.1.14. "Implicit Conversions")
says:

  "There are no implicit array or structure conversions. For
   example, an array of int cannot be implicitly converted to an
   array of float."

So let's add a check in place when assigning array initializers to
implicitly sized arrays, to avoid incorrectly allowing code on the
form:

int[] foo = float[](1.0, 2.0, 3.0)

This fixes the following dEQP test-cases:
- dEQP-GLES31.functional.shaders.implicit_conversions.es31.invalid.arrays.int_to_float_vertex
- dEQP-GLES31.functional.shaders.implicit_conversions.es31.invalid.arrays.int_to_float_fragment
- dEQP-GLES31.functional.shaders.implicit_conversions.es31.invalid.arrays.int_to_uint_vertex
- dEQP-GLES31.functional.shaders.implicit_conversions.es31.invalid.arrays.int_to_uint_fragment
- dEQP-GLES31.functional.shaders.implicit_conversions.es31.invalid.arrays.uint_to_float_vertex
- dEQP-GLES31.functional.shaders.implicit_conversions.es31.invalid.arrays.uint_to_float_fragment
- dEQP-GLES31.functional.shaders.implicit_conversions.es32.invalid.arrays.int_to_float_vertex
- dEQP-GLES31.functional.shaders.implicit_conversions.es32.invalid.arrays.int_to_float_fragment
- dEQP-GLES31.functional.shaders.implicit_conversions.es32.invalid.arrays.int_to_uint_vertex
- dEQP-GLES31.functional.shaders.implicit_conversions.es32.invalid.arrays.int_to_uint_fragment
- dEQP-GLES31.functional.shaders.implicit_conversions.es32.invalid.arrays.uint_to_float_vertex
- dEQP-GLES31.functional.shaders.implicit_conversions.es32.invalid.arrays.uint_to_float_fragment

Signed-off-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>