Makefile: allow recursion

When crosstool-NG is used standalone, we completely avoid recursion,
because the Makefile calls itself only once.

But when used as the buildroot toolchain backend, there is already
one level of make recursion when we first call the crosstool-NG
Makefile. And when buildroot is used out-of-tree, we are already
at the second level of recursion when calling the crosstool-NG
Makefile.

So, to cope with the situation, just get rid of the recursion test.

This probably won't go upstream.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

diff -du crosstool-ng-1.12.0/Makefile.in host-crosstool-ng-1.12.0/Makefile.in
--- crosstool-ng-1.12.0/Makefile.in     2011-08-01 01:21:34.000000000 +0200
+++ host-crosstool-ng-1.12.0/Makefile.in        2011-08-07 21:39:16.055958219 +0200
@@ -95,9 +95,14 @@
 # level.
 # This has the side effect of only showing the real targets, and hiding our
 # internal ones. :-)
-ifneq ($(MAKELEVEL),0)
-$(error Recursion detected, bailing out...)
-endif
+#
+# NB: For buildroot, this has no importance:
+# - crosstool-NG should never ever be called manually
+# - thus auto-completion would never ever be attempted
+# - so we shouldn't have to detect it
+#ifneq ($(MAKELEVEL),0)
+#$(error Recursion detected, bailing out...)
+#endif
 
 MAKEFLAGS += $(CT_MAKEFLAGS)
 build install clean distclean uninstall: