Add a test to check whether in compat mode make detectes builtins

on the command line and really executes the shell instead of directly
executing the command.

tools/regression/usr.bin/make/shell/builtin/Makefile

@@ -0,0 +1,30 @@
+#
+# In compat mode (the default without -j) a line that contains no shell
+# meta characters and no shell builtins is not passed to the shell but
+# executed directly. In our example the ls line without meta characters
+# will really execute ls, while the line with meta characters will execute
+# our special shell.
+#
+# $FreeBSD$
+
+all: sh
+	@MAKEFLAGS= ${MAKE} -B no-builtin
+	@MAKEFLAGS= ${MAKE} -B builtin
+
+sh: sh.sh
+	@cp ${.CURDIR}/sh.sh ${.OBJDIR}/sh
+	@chmod +x ${.OBJDIR}/sh
+
+.ifmake builtin || no-builtin
+
+.SHELL: path="${.OBJDIR}/sh"
+
+.PHONY: builtin no-builtin
+
+builtin:
+	@exec ls -d .
+
+no-builtin:
+	@ls -d .
+
+.endif

tools/regression/usr.bin/make/shell/builtin/expected.status

@@ -0,0 +1 @@
+2

tools/regression/usr.bin/make/shell/builtin/expected.stderr

@@ -0,0 +1 @@
+make: don't know how to make sh.sh. Stop

tools/regression/usr.bin/make/shell/builtin/sh.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+# $FreeBSD$
+echo "$@"
+if ! test -t 0 ; then
+	cat
+fi

tools/regression/usr.bin/make/shell/builtin/test.t

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+# $FreeBSD$
+
+cd `dirname $0`
+. ../../common.sh
+
+desc_test()
+{
+	echo "Check that a command line with a builtin is passed to the shell."
+}
+
+eval_cmd $1