The Imlib2 has to be installed to reproduce the problem. (on ubuntu libimlib2)

The simple code does not compile and gives error (see make.log attachment)

#include <Imlib2.h>
#include <QtCore/QCoreApplication>

int main(int argc, char *argv[])
{
}

It compiles fine if the include lines are swapped like this:

#include <QtCore/QCoreApplication>
#include <Imlib2.h>

int main(int argc, char *argv[])
{
}

The test code is attached.