[PyQt] dbus build error with latest pyqt5 snapshot

[Baz Walter]

Using the latest pyqt5 snapshot (1604061336), I get an error at the end 
of the build that dbus/dbus-python.h couldn't be found.

Looking at the diff for configure.py, I see that the qmake_quote 
function is now used on the includepath in generate_module_makefile. The 
problem is that the includepath for dbus is a *list* of paths, which 
means that the spaces *between* the paths are being wrongly escaped. 
This results in the list being treated as a single path, which is 
obviously why the header can't be found later.

In an attempt to overcome this issue, I came across another problem. I 
tried specifying a single include path using the --dbus option, thinking 
that this would result in the defaults being over-ridden. But I was 
puzzled to find that this only results in the user-specified path being 
*appended* to the list of defaults.

When I look at the check_dbus function, I see that it is *only* the 
user-specified path that is checked. If the check fails, the defaults 
aren't also checked (which makes sense), and the dbus support is 
disabled. But if the check succeeds, for some reason the defaults are 
still used, and are also given priority over the user-specified path 
(which I don't understand). Is there a reason why it is done this way?

-- 
Regards
Baz Walter