bash: set cache-file to /dev/null, breaks cross-compiling otherwise

Signed-off-by: Phil Sutter <phil.sutter@viprinet.com>

package/bash/Makefile

@@ -17,6 +17,7 @@ include $(TOPDIR)/mk/package.mk
 $(eval $(call PKG_template,BASH,${PKG_NAME},${PKG_VERSION}-${PKG_RELEASE},${PKG_DEPENDS},${PKG_DESCR},${PKG_SECTION}))
 
 CONFIGURE_ENV+=		bash_cv_getenv_redef=no
+CONFIGURE_ARGS+=	--cache-file=/dev/null
 XAKE_FLAGS+=		LIBS_FOR_BUILD=''
 
 post-install: