glsl: Fix input/output structure matching across shader stages

glsl: Fix input/output structure matching across shader stages

Section 7.4.1 (Shader Interface Matching) of the OpenGL 4.30 spec says:

    "Variables or block members declared as structures are considered
     to match in type if and only if structure members match in name,
     type, qualification, and declaration order."

Fixes:
     * layout-location-struct.shader_test

v2: rebased against master and small fixes

Signed-off-by: Vadym Shovkoplias <vadym.shovkoplias@globallogic.com>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108250