sh: Add some simple tests for ., exec and return from . script.

tools/regression/bin/sh/builtins/dot1.0

@@ -0,0 +1,21 @@
+# $FreeBSD$
+
+failures=
+failure() {
+	echo "Error at line $1" >&2
+	failures=x$failures
+}
+
+T=$(mktemp -d ${TMPDIR:-/tmp}/sh-test.XXXXXX) || exit
+trap 'rm -rf $T' 0
+cd $T || exit 3
+unset x
+echo 'x=2' >testscript
+. ./testscript
+[ "$x" = 2 ] || failure $LINENO
+cd / || exit 3
+x=1
+PATH=$T:$PATH . testscript
+[ "$x" = 2 ] || failure $LINENO
+
+test -z "$failures"

tools/regression/bin/sh/builtins/exec1.0

@@ -0,0 +1,25 @@
+# $FreeBSD$
+
+failures=
+failure() {
+	echo "Error at line $1" >&2
+	failures=x$failures
+}
+
+(
+	exec >/dev/null
+	echo bad
+)
+[ $? = 0 ] || failure $LINENO
+(
+	exec sh -c 'exit 42'
+	echo bad
+)
+[ $? = 42 ] || failure $LINENO
+(
+	exec /var/empty/nosuch
+	echo bad
+) 2>/dev/null
+[ $? = 127 ] || failure $LINENO
+
+test -z "$failures"

tools/regression/bin/sh/builtins/return4.0

@@ -0,0 +1,16 @@
+# $FreeBSD$
+
+failures=
+failure() {
+	echo "Error at line $1" >&2
+	failures=x$failures
+}
+
+T=$(mktemp -d ${TMPDIR:-/tmp}/sh-test.XXXXXX) || exit
+trap 'rm -rf $T' 0
+cd $T || exit 3
+echo 'return 42; exit 4' >testscript
+. ./testscript
+[ "$?" = 42 ] || failure $LINENO
+
+test -z "$failures"