kconfig: error out when seeing recursive dependency

Originally, recursive dependency was a fatal error for Kconfig
because Kconfig cannot compute symbol values in such a situation.

Commit d595cea624 ("kconfig: print more info when we see a recursive
dependency") changed it to a warning, which I guess was not intentional.

Get it back to an error again.

Also, rename the unit test directory "warn_recursive_dep" to
"err_recursive_dep" so that it matches to the behavior.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: Dirk Gouders <dirk@gouders.net>

scripts/kconfig/tests/err_recursive_dep/Kconfig

@@ -0,0 +1,62 @@
+# depends on itself
+
+config A
+	bool "A"
+	depends on A
+
+# select itself
+
+config B
+	bool
+	select B
+
+# depends on each other
+
+config C1
+	bool "C1"
+	depends on C2
+
+config C2
+	bool "C2"
+	depends on C1
+
+# depends on and select
+
+config D1
+	bool "D1"
+	depends on D2
+	select D2
+
+config D2
+	bool
+
+# depends on and imply
+# This is not recursive dependency
+
+config E1
+	bool "E1"
+	depends on E2
+	imply E2
+
+config E2
+	bool "E2"
+
+# property
+
+config F1
+	bool "F1"
+	default F2
+
+config F2
+	bool "F2"
+	depends on F1
+
+# menu
+
+menu "menu depending on its content"
+	depends on G
+
+config G
+	bool "G"
+
+endmenu