logic: Fixes and improvements for C/C++ compiler header path handling

* Always add compiler header path when prefilling on first start, regardless of successful detection
* Show compiler header path in path list box on top and readonly
* Prepend compiler header path on Windows in system header path compiler flags, append otherwise
* Show warning when saving ApplicationSettings if compiler header path is not in global include paths
* Show warning when saving ApplicationSettings if there is another path containing compiler headers

src/lib/utility/ResourcePaths.cpp

@@ -34,5 +34,5 @@ FilePath ResourcePaths::getJavaPath()
 
 FilePath ResourcePaths::getCxxCompilerHeaderPath()
 {
-	return AppPath::getAppPath().concatenate(L"data/cxx/include/");
+	return AppPath::getAppPath().concatenate(L"data/cxx/include/").getCanonical();
 }

src/lib/utility/utilityCxx.cpp

@@ -1,30 +1,23 @@
 #include "utilityCxx.h"
 
 #include "ResourcePaths.h"
-#include "utilityApp.h"
 
 namespace utility
 {
 	std::vector<FilePath> replaceOrAddCxxCompilerHeaderPath(const std::vector<FilePath>& headerSearchPaths)
 	{
 		std::vector<FilePath> newHeaderSearchPaths;
+		const FilePath cxxCompilerHeaderPath = ResourcePaths::getCxxCompilerHeaderPath();
 
-		if (utility::getOsType() == OS_WINDOWS)
+		for (const FilePath& path : headerSearchPaths)
 		{
-			newHeaderSearchPaths = headerSearchPaths;
-		}
-		else
-		{
-			for (const FilePath& path : headerSearchPaths)
+			if (path != cxxCompilerHeaderPath)
 			{
-				if (!path.getConcatenated(L"/stdarg.h").exists())
-				{
-					newHeaderSearchPaths.push_back(path);
-				}
+				newHeaderSearchPaths.push_back(path);
 			}
 		}
 
-		newHeaderSearchPaths.push_back(ResourcePaths::getCxxCompilerHeaderPath().getCanonical());
+		newHeaderSearchPaths.push_back(cxxCompilerHeaderPath);
 		return newHeaderSearchPaths;
 	}
 }