This PR improves the experience for debugging tools that consume SPIR-V
produced by passing in-memory strings to dxcompiler.dll. When dxc.exe is
used, OpSource and OpDebugSource are populated by reading original
source from the filesystem. dxcompiler.dll users instead find their
input string is preprocessed, which is confusing behavior.
Contrary to the leading comment in the code this change modifies,
debugging tools do not want preprocessed source. Such tools show and
allow editing of include files. If everything is pasted into a single
source string, finding what to edit is difficult. Editing the
preprocessed source has the additional complication that a user would
have to edit also the #line markers, which is hard to get right
manually. In the preprocessed source, all comments are lost, which makes
it hard to read the code. Finally in preprocessed source, all macros and
code under conditional compilation are lost. That will make it
impossible to modify those parts in an edit.
Co-authored-by: Steve Urquhart <stevur01@ntd.nintendo.com>
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