What path specifically goes into PKG_CONFIG_PATH?

edit

Trying to compile kino I am facing a few challenges which did not exist in the previous version of Fedora that I am upgrading from. End of configure output:

checking for pkg-config... /usr/bin/pkg-config
checking pkg-config is at least version 0.9.0... yes
checking for LIBDV... configure: error: Package requirements (libdv >= 0.103) were not met:

Package 'libdv', required by 'virtual:world', not 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 LIBDV_CFLAGS
and LIBDV_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.

These instructions are not clear enough, so my first thought was to check if libdv was installed:

[use0@localhost kino-1.3.4]$ dnf provides libdv
libdv-1.0.0-23.fc26.x86_64 : Software decoder for DV format video
Repo        : @System
Matched from:
Provide    : libdv = 1.0.0-23.fc26

libdv-1.0.0-23.fc26.i686 : Software decoder for DV format video
Repo        : fedora
Matched from:
Provide    : libdv = 1.0.0-23.fc26

libdv-1.0.0-23.fc26.x86_64 : Software decoder for DV format video
Repo        : fedora
Matched from:
Provide    : libdv = 1.0.0-23.fc26

It is already installed either by the initial OS setup, or as a dependency for another package (possibly VLC):

[use0@localhost kino-1.3.4]$ sudo dnf install -y libdv-1.0.0-23.fc26.x86_64
Last metadata expiration check: 0:32:34 ago on Fri 20 Apr 2018 08:02:37 PM EDT.
Package libdv-1.0.0-23.fc26.x86_64 is already installed, skipping.
Dependencies resolved.
Nothing to do.
Complete!

So at this point I do not understand what is missing for configure and what has to be done to satisfy its requirement for libdv. Please explain!