Fix the error message for when an erroneous HLSL constructor statement
is detected.
Prior to this change, such error messages would not show correct file
path and line number information.
Additionally, update test data to account for updated error messages.
Translate printf() to what GL_EXT_debug_printf has done. HLSL could
define non-constant string variable and we don't have such features
in SPIR-V, so just support constant string variable.
Now that the HLSL source files are part of the `glslang` target (#2271), it makes sense for these to sit in the `glslang` directory.
Changed the case of the directory from `hlsl` to `HLSL` to better match the sibling directories.
