fix compile errors by forcing bash to be used as a shell in all submake processes

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@22726 3c298f89-4303-0410-b956-a3cf2f4a3e73

include/toplevel.mk

@@ -7,7 +7,6 @@
 #
 
 RELEASE:=Kamikaze
-export SHELL:=/usr/bin/env bash
 PREP_MK= OPENWRT_BUILD= QUIET=0
 
 include $(TOPDIR)/include/verbose.mk

rules.mk

@@ -36,6 +36,7 @@ TARGET_OPTIMIZATION:=$(call qstrip,$(CONFIG_TARGET_OPTIMIZATION))
 TARGET_SUFFIX=$(call qstrip,$(CONFIG_TARGET_SUFFIX))
 BUILD_SUFFIX:=$(call qstrip,$(CONFIG_BUILD_SUFFIX))
 SUBDIR:=$(patsubst $(TOPDIR)/%,%,${CURDIR})
+export SHELL:=/usr/bin/env bash
 
 OPTIMIZE_FOR_CPU=$(subst i386,i486,$(ARCH))