/usr/lib/x86_64-linux-gnu/pkgconfig/IL.pc is in libdevil-dev 1.7.8-10.
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=${prefix}
Name: IL
Description: Developer's Image Library - IL part (just image loading)
Version: 1.7.8
URL: http://openil.sourceforge.net
Libs: -L${prefix}/lib/x86_64-linux-gnu -lIL
Libs.private: -ltiff -lpng12 -lmng -llcms2 -ljpeg
Cflags: -I${prefix}/include
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