Dear Maintainer,
the pkg-config file libchipcard-client.pc is not usable as-is:
$ pkg-config libchipcard-client --cflags
Variable 'datadir' not defined in '/usr/lib/x86_64-linux-gnu/pkgconfig/libchipcard-client.pc'
pkgdatadir is defined before datadir, but depends on the latter:
$ pkg-config --debug libchipcard-client --cflags
Error printing enabled by default due to use of output options besides --exists, --atleast/exact/max-version or --list-all. Value of --silence-errors: 0
Error printing enabled
Adding virtual 'pkg-config' package to list of known packages
Looking for package 'libchipcard-client'
Looking for package 'libchipcard-client-uninstalled'
Reading 'libchipcard-client' from file '/usr/lib/x86_64-linux-gnu/pkgconfig/libchipcard-client.pc'
Parsing package file '/usr/lib/x86_64-linux-gnu/pkgconfig/libchipcard-client.pc'
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line>prefix=/usr
Variable declaration, 'prefix' has value '/usr'
line>exec_prefix=${prefix}
Variable declaration, 'exec_prefix' has value '/usr'
line>libdir=${prefix}/lib/x86_64-linux-gnu
Variable declaration, 'libdir' has value '/usr/lib/x86_64-linux-gnu'
line>includedir=${prefix}/include
Variable declaration, 'includedir' has value '/usr/include'
line>pkgdatadir=${datadir}/chipcard
Variable 'datadir' not defined in '/usr/lib/x86_64-linux-gnu/pkgconfig/libchipcard-client.pc'