Defer capability decl for ClipDistance, CullDistance, PointSize until actual use

The compiler will mark struct members with those builtins, but won't
declare the capability until that member is accessed by some executable
instruction.

Test changes:
- spv.430.vert: was missing ClipDistance capability.
- spv.precise.tese: remove TessellationPointSize capability.

Test/baseResults/spv.430.vert.out

@@ -10,6 +10,7 @@ Linked vertex stage:
 // Id's are bound by 66
 
                               Capability Shader
+                              Capability ClipDistance
                1:             ExtInstImport  "GLSL.std.450"
                               MemoryModel Logical GLSL450
                               EntryPoint Vertex 4  "main" 12 23 34 38 41 42 62 65

Test/baseResults/spv.precise.tese.out

@@ -10,7 +10,6 @@ Linked tessellation evaluation stage:
 // Id's are bound by 119
 
                               Capability Tessellation
-                              Capability TessellationPointSize
                1:             ExtInstImport  "GLSL.std.450"
                               MemoryModel Logical GLSL450
                               EntryPoint TessellationEvaluation 4  "main" 12 21 62 112