glsl: Move and refine test for unsized arrays in GLSL ES

glsl: Move and refine test for unsized arrays in GLSL ES

GLSL ES does not allow unsized arrays, and GLSL ES 1.00 does not allow
array initializers.  However, GLSL ES 3.00 allows array initializers,
and the initializer can explicitly size the array.  The specification
even includes some examples of this:

    float x[] = float[2] (1.0, 2.0);     // declares an array of size 2
    float y[] = float[] (1.0, 2.0, 3.0); // declares an array of size 3

    float a[5];
    float b[] = a;

Move the unsized array check to after the initializer has been
processed.  If the array is still unsized, generate the error.  This
should have no effect in GLSL ES 1.00 because, as previously mentioned,
array initializers are not allowed.

Fixes piglit "glsl-es-3.00 compiler array-sized-by-initializer.vert".

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Cc: "9.1 9.2" <mesa-stable@lists.freedesktop.org>