HLSL: Refactor attribute implementation.

- make it sharable with GLSL
- correct the case insensitivity
- remove the map; queries are not needed, all entries need processing
- make it easier to build bottom up (will help GLSL parsing)
- support semantic checking and reporting
- allow front-end dependent semantics and attribute name mapping

glslang/CMakeLists.txt

@@ -9,6 +9,7 @@ endif(WIN32)
 set(SOURCES
     MachineIndependent/glslang.y
     MachineIndependent/glslang_tab.cpp
+    MachineIndependent/attribute.cpp
     MachineIndependent/Constant.cpp
     MachineIndependent/iomapper.cpp
     MachineIndependent/InfoSink.cpp
@@ -51,6 +52,7 @@ set(HEADERS
     Include/revision.h
     Include/ShHandle.h
     Include/Types.h
+    MachineIndependent/attribute.h
     MachineIndependent/glslang_tab.cpp.h
     MachineIndependent/gl_types.h
     MachineIndependent/Initialize.h