CMake: Improve remote parsing speed

To improve the speed of parsing the result of a remote
cmake call, we move the file fetching and parsing into a
mapped concurrent call.

We also first uniquify the list of files to remove duplicates.

Fixes: QTCREATORBUG-29618
Change-Id: I18108928ba3b5f4f8ec3d5610b216c5ccf060877
Reviewed-by: Cristian Adam <cristian.adam@qt.io>

src/plugins/cmakeprojectmanager/fileapidataextractor.h

@@ -28,6 +28,8 @@ public:
     bool operator==(const CMakeFileInfo& other) const { return path == other.path; }
     friend size_t qHash(const CMakeFileInfo &info, uint seed = 0) { return qHash(info.path, seed); }
 
+    bool operator<(const CMakeFileInfo &other) const { return path < other.path; }
+
     Utils::FilePath path;
     bool isCMake = false;
     bool isCMakeListsDotTxt = false;