Merge branch 'bug137-fix-spirv_assembly.instruction.graphics.module-geom-var-decls...

Merge branch 'bug137-fix-spirv_assembly.instruction.graphics.module-geom-var-decls' into 'master'

Fix 137: bad geom entry point I/O var declarations

Fix declarations of Input and Output declarations in test
dEQP-VK.spirv_assembly.instruction.graphics.module.*
They were missing "geom_" prefices.

Changed:

    OpEntryPoint Geometry %geom_main "main" %out_gl_position %gl_in
      %out_color %in_color

To the following, to match usage in the function bodies:

    OpEntryPoint Geometry %geom_main "main" %geom_out_gl_position
       %geom_gl_in %geom_out_color %geom_in_color

Also fix associated OpDecorate instructions.

Fixes #137

See merge request !238