Disable job control when running 'sh -i' in the testsuite.

Job control tty manipulations sometimes cause the tests to stop (SIGTTOU
and the like) when run from the 'prove' tool.

tools/regression/bin/sh/builtins/fc1.0

@@ -8,7 +8,7 @@ T=$(mktemp -d sh-test.XXXXXX)
 cd $T
 
 mkfifo input output error
-HISTFILE=/dev/null sh -i <input >output 2>error &
+HISTFILE=/dev/null sh +m -i <input >output 2>error &
 {
 	# Syntax error
 	echo ')' >&3

tools/regression/bin/sh/errors/backquote-error1.0

@@ -1,4 +1,4 @@
 # $FreeBSD$
 
-echo 'echo `for` echo ".BAD"CODE.' | sh -i 2>&1 | grep -q BADCODE && exit 1
+echo 'echo `for` echo ".BAD"CODE.' | sh +m -i 2>&1 | grep -q BADCODE && exit 1
 exit 0