Updating init scripts to have more robust grepping

The previous pattern could accidentally match on things like
'real_root=ZFS=node02-zp00/ROOT/rootfs' due to the 'ZFS=no'
substring.

Signed-off-by: Matthew Thode <mthode@mthode.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1837

etc/init.d/zfs.fedora.in

@@ -27,7 +27,7 @@ export PATH=/usr/local/sbin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin
 
 if [ -z "$init" ]; then
     # Not interactive
-    grep -Eqi 'zfs=off|zfs=no' /proc/cmdline && exit 3
+    grep -qE '(^|[^\\](\\\\)* )zfs=(off|no)( |$)' /proc/cmdline && exit 3
 fi
 
 # Source function library & LSB routines

etc/init.d/zfs.gentoo.in

@@ -5,7 +5,7 @@
 
 if [ -z "$init" ]; then
     # Not interactive
-    grep -Eqi 'zfs=off|zfs=no' /proc/cmdline && exit 3
+    grep -qE '(^|[^\\](\\\\)* )zfs=(off|no)( |$)' /proc/cmdline && exit 3
 fi
 
 depend()

etc/init.d/zfs.lsb.in

@@ -38,7 +38,7 @@ ZPOOL_CACHE="@sysconfdir@/zfs/zpool.cache"
 
 if [ -z "$init" ]; then
     # Not interactive
-    grep -Eqi 'zfs=off|zfs=no' /proc/cmdline && exit 3
+    grep -qE '(^|[^\\](\\\\)* )zfs=(off|no)( |$)' /proc/cmdline && exit 3
 fi
 
 start()

etc/init.d/zfs.lunar.in

@@ -16,7 +16,7 @@ ZPOOL_CACHE="@sysconfdir@/zfs/zpool.cache"
 
 if [ -z "$init" ]; then
     # Not interactive
-    grep -Eqi 'zfs=off|zfs=no' /proc/cmdline && exit 3
+    grep -qE '(^|[^\\](\\\\)* )zfs=(off|no)( |$)' /proc/cmdline && exit 3
 fi
 
 case $1 in

etc/init.d/zfs.redhat.in

@@ -27,7 +27,7 @@ export PATH=/usr/local/sbin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin
 
 if [ -z "$init" ]; then
     # Not interactive
-    grep -Eqi 'zfs=off|zfs=no' /proc/cmdline && exit 3
+    grep -qE '(^|[^\\](\\\\)* )zfs=(off|no)( |$)' /proc/cmdline && exit 3
 fi
 
 # Source function library & LSB routines