libclang 3.8 seems to be sensitive to file paths separators [1]. On Windows,
this led to not updated document annotations and/or crashes after reparsing.
When passing file paths to libclang, convert to native separators.
When getting file paths from libclang, convert back.
This handles:
* main file path
* file paths of the unsaved files
* -I<DIR> arguments, the resource path (for builtins) and the paths to the
wrapped qt headers
* included header files from libclang
* source locations from libclang
Also, minimize the conversion in SourceLocation to a minimum by making
filePath() lazy.
[1] https://llvm.org/bugs/show_bug.cgi?id=28381
Change-Id: If5866f34a6fdc6b34b16c022d3988e8e6eae2a0a
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
36e7f4541f