sh: Add test cases for break outside a loop.

In most shells (including our sh), break outside a loop does nothing with
status 0, or at least does not abort. Therefore, scripts sometimes (buggily)
depend on this.

tools/regression/bin/sh/builtins/break4.4

@@ -0,0 +1,7 @@
+# $FreeBSD$
+
+# Although this is not specified by POSIX, some configure scripts (gawk 4.1.0)
+# appear to depend on it.
+
+break
+exit 4

tools/regression/bin/sh/builtins/break5.4

@@ -0,0 +1,12 @@
+# $FreeBSD$
+
+# Although this is not specified by POSIX, some configure scripts (gawk 4.1.0)
+# appear to depend on it.
+# In some uncommitted code, the subshell environment corrupted the outer
+# shell environment's state.
+
+(for i in a b c; do
+	exit 3
+done)
+break
+exit 4