/usr/lib/x86_64-linux-gnu/pkgconfig/dri.pc is in mesa-common-dev-lts-trusty 10.1.3-0ubuntu0.2~precise2.
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 11 | prefix=/usr
exec_prefix=${prefix}
libdir=${prefix}/lib/x86_64-linux-gnu
includedir=${prefix}/include
dridriverdir=/usr/lib/x86_64-linux-gnu/dri
Name: dri
Description: Direct Rendering Infrastructure
Version: 10.1.3
Requires.private: libdrm >= 2.4.24
Cflags: -I${includedir}
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