Bug#899382: qt5-qmake: cross wrapper should supply PKG_CONFIG_EXECUTABLE

[Helmut Grohne <helmut@subdivi.de>]

Package: qt5-qmake
Version: 5.10.1+dfsg-7
User: helmutg@debian.org
Usertags: rebootstrap
Control: affects -1 + src:qtmultimedia-opensource-src

qtmultimedia-opensource-src fails to cross build from source, because it
fails finding gstreamer and pulseaudio. Looking at its configure.json, I
see that the ones that are failing are discovered using a "type":
"pkgConfig" check. This one is implemented in the function
qtConfLibrary_pkgConfig in
/usr/lib/<triplet>/qt5/mkspecs/features/qt_configure.prf. It discovers
the pkg-config to use from the function qtConfPkgConfig in the same
file. This function does not look at the PKG_CONFIG variable, but
insists on using the PKG_CONFIG_EXECUTABLE variable. Thus the qmake
cross wrapper should also supply PKG_CONFIG_EXECUTABLE in addition to
PKG_CONFIG with the same value.

If you think this is insane, please blame qt upstream. I'd join you.

Helmut