gplugin/gplugin

069c014ed85f
Make the names inside the .pc files match the pc filename

As far as I can tell this is purely cosmetic, but it should probably match nonetheless.

Testing Done:
ran `PKG_CONFIG_PATH=$(pwd)/meson-private pkg-config --modversion` from the build directory with and without the patch and made sure there was no difference.

Reviewed at https://reviews.imfreedom.org/r/935/
The following individuals have contributed to this project.
Ankit Vani <a@nevitus.org>
EionRobb <eion@robbmob.com>
Elliott Sales de Andrade <quantum.analyst@gmail.com>
Gary Kramlich <grim@reaperworld.com>
ivanhoe <ivanhoe@fiscari.de>
Jason Scherer <schereja@gmail.com>
John Bailey <rekkanoryo@rekkanoryo.org>
Mike Ruprecht <cmaiku@gmail.com>
Olaf Hering <olaf@aepfle.de>
Richard Laager <rlaager@pidgin.im>
Sorvival <sorvival@tutanota.com>