ClangSupport: Use simpler structures in some cases

The patch is mostly mechanical, but contains also a few spurious changes
from values references for some local variables, foreach -> ranged for
etc that I coulnd't resist.

Change-Id: I58f0bd972546895eb318607cbfbd7ac35caf3f23
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

src/plugins/clangpchmanager/projectupdater.cpp

@@ -185,7 +185,7 @@ Utils::PathStringVector ProjectUpdater::createExcludedPaths(
     excludedPaths.reserve(generatedFiles.size());
 
     auto convertToPath = [] (const ClangBackEnd::V2::FileContainer &fileContainer) {
-        return fileContainer.filePath().path();
+        return fileContainer.filePath.path();
     };
 
     std::transform(generatedFiles.begin(),