glsl/linker: link-error using the same name in unnamed block and outside

glsl/linker: link-error using the same name in unnamed block and outside

According with OpenGL GLSL 4.20 spec, section 4.3.9, page 57:

   "It is a link-time error if any particular shader interface
    contains:
      - two different blocks, each having no instance name, and each
        having a member of the same name, or
      - a variable outside a block, and a block with no instance name,
        where the variable has the same name as a member in the block."

This means that it is a link error if for example we have a vertex
shader with the following definition.

  "layout(location=0) uniform Data { float a; float b; };"

and a fragment shader with:

  "uniform float a;"

As in both cases we refer to both uniforms as "a", and thus using
glGetUniformLocation() wouldn't know which one we mean.

This fixes KHR-GL*.shaders.uniform_block.common.name_matching.

v2: add fixed tests (Tapani)

Reviewed-by: Tapani Pälli <tapani.palli@intel.com>