install path fixes

* rpm: correct pkgconfig path

pkconfig files get installed to $datarootdir/pkgconfig but rpm expects
them to be at $datadir. This works when $datarootdir==$datadir which is
the case most of the time but will fail when they differ.

* install: make initramfs-tools path static

Since initramfs-tools' path is nothing we can control as it is an
external package it does not make any sense to install zfs additions
anywhere else. Simply use /usr/share/initramfs-tools as path.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Closes #9087

contrib/initramfs/Makefile.am

@@ -1,4 +1,4 @@
-initrddir = $(datarootdir)/initramfs-tools
+initrddir = /usr/share/initramfs-tools
 
 initrd_SCRIPTS = \
 	conf.d/zfs conf-hooks.d/zfs hooks/zfs scripts/zfs scripts/local-top/zfs

contrib/initramfs/hooks/Makefile.am

@@ -1,4 +1,4 @@
-hooksdir = $(datarootdir)/initramfs-tools/hooks
+hooksdir = /usr/share/initramfs-tools/hooks
 
 hooks_SCRIPTS = \
 	zfs

contrib/initramfs/scripts/Makefile.am

@@ -1,4 +1,4 @@
-scriptsdir = $(datarootdir)/initramfs-tools/scripts
+scriptsdir = /usr/share/initramfs-tools/scripts
 
 scripts_DATA = \
 	zfs

contrib/initramfs/scripts/local-top/Makefile.am

@@ -1,3 +1,3 @@
-localtopdir = $(datarootdir)/initramfs-tools/scripts/local-top
+localtopdir = /usr/share/initramfs-tools/scripts/local-top
 
 EXTRA_DIST = zfs

rpm/generic/zfs.spec.in

@@ -458,8 +458,8 @@ systemctl --system daemon-reload >/dev/null || true
 %{_libdir}/libzfs*.so.*
 
 %files -n libzfs2-devel
-%{_datadir}/pkgconfig/libzfs.pc
-%{_datadir}/pkgconfig/libzfs_core.pc
+%{_datarootdir}/pkgconfig/libzfs.pc
+%{_datarootdir}/pkgconfig/libzfs_core.pc
 %{_libdir}/*.so
 %{_includedir}/*
 %doc AUTHORS COPYRIGHT LICENSE NOTICE README.md