/usr/lib/pkgconfig/libagg.pc is in libagg-dev 1:2.4-r127+dfsg1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 | prefix=/usr
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir=${prefix}/include/agg2
Name: libagg
Description: Anti Grain Geometry - A High Quality Rendering Engine for C++
Version: 2.4.0
Libs: -L${libdir} -lagg_pic
Cflags: -I${includedir}
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