Bug#893067: libinput-dev: pkg-config file does not work without libwacom-dev installed

[Daniel Schepler <dschepler@gmail.com>]

Package: libinput-dev
Version: 1.10.3-1
Severity: important
Justification: causing numerous new FTBFS bugs

In a clean pbuilder chroot:

# apt install libinput-dev pkg-config
# pkg-config --cflags libinput
Package libwacom was not found in the pkg-config search path.
Perhaps you should add the directory containing 'libwacom.pc'
to the PKG_CONFIG_PATH environment variable
Package 'libwacom', required by 'libinput', not found
# pkg-config --exists libinput
# echo $?
1

I've been seeing several new FTBFS issues in other packages due to
this, either due to configure scripts erroring out when they find
libinput "does not exist", or in the case of qtbase-opensource-src,
the configuration leaves out the libinput plugin which then causes an
error at dh_install time.
-- 
Daniel