torture: Make TORTURE_TRUST_MAKE available in kvm-again.sh environment

Because the TORTURE_TRUST_MAKE environment variable is not recorded,
kvm-again.sh runs can result in the parse-build.sh script emitting
false-positive "BUG: TREE03 no build" messages.  These messages are
intended to complain about any lack of compiler invocations when the
--trust-make flag is not given to kvm.sh.  However, when this flag is
given to kvm.sh (and thus when TORTURE_TRUST_MAKE=y), lack of compiler
invocations is expected behavior when rebuilding from identical source
code.

This commit therefore makes kvm-test-1-run.sh record the value of the
TORTURE_TRUST_MAKE environment variable as an additional comment in the
qemu-cmd file, and also makes kvm-again.sh reconstitute that variable
from that comment.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/testing/selftests/rcutorture/bin/kvm-again.sh

@@ -161,6 +161,11 @@ do
 	fi
 	echo "# TORTURE_KCONFIG_GDB_ARG=''" >> $i
 done
+
+# Extract settings from the last qemu-cmd file transformed above.
+grep '^#' $i | sed -e 's/^# //' > $T/qemu-cmd-settings
+. $T/qemu-cmd-settings
+
 grep -v '^#' $T/batches.oldrun | awk '
 BEGIN {
 	oldbatch = 1;

tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh

@@ -204,6 +204,7 @@ echo "# seconds=$seconds" >> $resdir/qemu-cmd
 echo "# TORTURE_KCONFIG_GDB_ARG=\"$TORTURE_KCONFIG_GDB_ARG\"" >> $resdir/qemu-cmd
 echo "# TORTURE_JITTER_START=\"$TORTURE_JITTER_START\"" >> $resdir/qemu-cmd
 echo "# TORTURE_JITTER_STOP=\"$TORTURE_JITTER_STOP\"" >> $resdir/qemu-cmd
+echo "# TORTURE_TRUST_MAKE=\"$TORTURE_TRUST_MAKE\"; export TORTURE_TRUST_MAKE" >> $resdir/qemu-cmd
 
 if test -n "$TORTURE_BUILDONLY"
 then