Comment 31 for bug 1623666

I've just noticed that I have essentially the same problem after making a new bug report at https://bugs.launchpad.net/ubuntu/+source/libimobiledevice/+bug/1654833 which I've now marked as duplicate.

This bug affects both iOS 9.3.5 (iPad) and iOS 10.2 (iPhone) since upgrading to Ubuntu 16.10 (64-bit) probably including a new version of this libimobiledevice package (libimobiledevice6 version 1.2.0+dfsg-3ubuntu1)

Attempting to implement the workaround suggested here I've got stuck at the very first step:
The command "./autogen.sh --prefix=/usr/local/libimobiledevice" displayed this error message:

configure: error: Package requirements (libusbmuxd >= 1.0.9) were not met:
No package 'libusbmuxd' found
Consider adjusting the PKG_CONFIG_PATH environment variable if you installed software in a non-standard prefix.
Alternatively, you may set the environment variables libusbmuxd_CFLAGS and libusbmuxd_LIBS to avoid the need to call pkg-config.

I have the files "/usr/lib/x86_64-linux-gnu/libusbmuxd.so.4" (a symlink) and "/usr/lib/x86_64-linux-gnu/libusbmuxd.so.4.0.0" but I don't know how to make them accessible by this script.
I also have the file "/usr/lib/pkg-config.multiarch" which includes "x86_64-linux-gnu" so I guess pkg-config should know where to look for :-(