/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/ is in libslepc3.4.2-dev 3.4.2.dfsg-1build1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcconf.h
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcds.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcdsdef.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepceps.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcepsdef.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcip.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcipdef.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcmfn.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcmfndef.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcnep.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcnepdef.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcqep.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcqepdef.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcst.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcstdef.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcsvd.mod
/usr/lib/slepcdir/3.4.2/linux-gnu-c-opt/include/slepcsvddef.mod