logic: Fixes in header path detection

* Rerun header path detection when only cxx header path is present after update in migration
* Check if path exists in header and framework path detection on mac/linux

src/lib/settings/ApplicationSettings.cpp

@@ -87,6 +87,11 @@ bool ApplicationSettings::load(const FilePath& filePath, bool readOnly)
 			cxxHeaderSearchPaths = utility::replaceOrAddCxxCompilerHeaderPath(cxxHeaderSearchPaths);
 
 			migration->setValuesInSettings(settings, "indexing/cxx/header_search_paths/header_search_path", cxxHeaderSearchPaths);
+
+			if (cxxHeaderSearchPaths.size() == 1)
+			{
+				migration->setValueInSettings(settings, "indexing/cxx/has_prefilled_header_search_paths", false);
+			}
 		}
 	));
 

src/lib_gui/utility/path_detector/cxx_header/CxxFrameworkPathDetector.cpp

@@ -18,7 +18,11 @@ std::vector<FilePath> CxxFrameworkPathDetector::getPaths() const
 	{
 		if (utility::isPostfix<std::string>(" (framework directory)", path))
 		{
-			frameworkPaths.push_back(FilePath(utility::replace(path, " (framework directory)", "")).makeCanonical());
+			FilePath p = FilePath(utility::replace(path, " (framework directory)", "")).makeCanonical();
+			if (p.exists())
+			{
+				frameworkPaths.push_back(p);
+			}
 		}
 	}
 	return frameworkPaths;

src/lib_gui/utility/path_detector/cxx_header/CxxHeaderPathDetector.cpp

@@ -19,6 +19,7 @@ std::vector<FilePath> CxxHeaderPathDetector::getPaths() const
 	for (const std::string& path : paths)
 	{
 		if (!utility::isPostfix<std::string>(" (framework directory)", path) &&
+			FilePath(path).getCanonical().exists() &&
 			!FilePath(path).getCanonical().getConcatenated(L"/stdarg.h").exists())
 		{
 			headerSearchPaths.push_back(FilePath(path).makeCanonical());