cookbook/container: remove unexplained "exec >&2" lines.

These are often a good idea, but not necessary here and are distracting
to the tutorial, so let's just take them out.

Reported-by: Jeff Stearns <jeff.stearns@gmail.com>

docs/cookbook/container/all.do

@@ -1,4 +1,4 @@
-exec >&2
+exec >&2   # any output we produce is a log message
 no_simple=
 no_debian=
 no_runlocal=

docs/cookbook/container/debdownload.fs.do

@@ -1,4 +1,3 @@
-exec >&2
 fs=${1%.fs}
 
 # let's *not* delete this directory; it's okay if previously-downloaded
@@ -10,5 +9,5 @@ debootstrap \
 	--download-only \
 	--keep-debootstrap-dir \
 	$(cat debootstrap.options) \
-	"$fs"
+	"$fs" >&2
 redo-ifchange "$fs/debootstrap/debootstrap.log"

docs/cookbook/container/debian.fs.do

@@ -1,9 +1,9 @@
-exec >&2
 fs=${1%.fs}
 rm -rf "$fs" "$fs.fakeroot"
 
 redo-ifchange debootstrap.fs
-fakeroot -i debootstrap.fakeroot -s "$fs.fakeroot" cp -a debootstrap/. "$fs"
+fakeroot -i debootstrap.fakeroot -s "$fs.fakeroot" \
+	cp -a debootstrap/. "$fs" >&2
 
 # Work around bug (in fakechroot?) where /lib64 symlink ends up pointing
 # at an absolute path including $PWD, rather than inside the chroot.

docs/cookbook/container/debootstrap.fs.do

@@ -1,4 +1,3 @@
-exec >&2
 fs=${1%.fs}
 rm -rf "$fs" "$fs.fakeroot"
 
@@ -7,7 +6,7 @@ cp -a debdownload/. "$fs"
 eatmydata \
 	fakechroot \
 	fakeroot -s "$fs.fakeroot" \
-	debootstrap $(cat debootstrap.options) "$fs"
+	debootstrap $(cat debootstrap.options) "$fs" >&2
 
 # Clean up installed package files
 rm -f "$fs"/var/cache/apt/archives/*.deb \

docs/cookbook/container/default.runkvm.do

@@ -1,4 +1,3 @@
-exec >&2
 ./need.sh python kvm busybox
 
 redo-ifchange "$2.initrd" memcalc.py
@@ -7,7 +6,7 @@ rm -f "$3.out" "$3.code"
 # Linux only allows an initrd of size < 50% of RAM,
 # so set a RAM amount based on the initrd size.
 mem=$(./memcalc.py "$2.initrd")
-echo "$2: kvm memory required: $mem"
+echo "$2: kvm memory required: $mem" >&2
 
 kvm \
 	-m "$mem" \
@@ -21,7 +20,7 @@ kvm \
 	-chardev file,id=char2,path="$3.code" \
 	-serial chardev:char0 \
 	-serial chardev:char1 \
-	-serial chardev:char2
+	-serial chardev:char2 >&2
 read rv <$3.code || true
 [ -z "$rv" ] && exit 99
 if [ "$rv" -eq 0 ]; then

docs/cookbook/container/libs.fs.do

@@ -1,5 +1,3 @@
-exec >&2
-
 fs=${1%.fs}
 redo-ifchange simple.fs
 

docs/cookbook/container/simple.fs.do

@@ -1,5 +1,3 @@
-exec >&2
-
 # We can pull in the 'hello' binary built in an earlier
 # example.  Notice that it's safe to have dependencies
 # that cross directory boundaries, even when we're building