glsl: process bindless/bound layout qualifiers

This adds bindless_sampler and bound_sampler (and respectively
bindless_image and bound_image) to the parser.

v3: - add an extra space in apply_bindless_qualifier_to_variable()
    - fix indentation in merge_qualifier()

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

src/compiler/glsl/ir.h

@@ -849,6 +849,18 @@ public:
        */
       unsigned fb_fetch_output:1;
 
+      /**
+       * Non-zero if this variable is considered bindless as defined by
+       * ARB_bindless_texture.
+       */
+      unsigned bindless:1;
+
+      /**
+       * Non-zero if this variable is considered bound as defined by
+       * ARB_bindless_texture.
+       */
+      unsigned bound:1;
+
       /**
        * Emit a warning if this variable is accessed.
        */