mdadm: pass CHECK_RUN_DIR=0 to the Makefile in order to fix build failure

This commit should fix build failures of mdadm 3.3:

  http://autobuild.buildroot.net/results/b4a/b4abc317d07b073f8be870ff0e7fee8f8c65f2ff/
  http://autobuild.buildroot.net/results/79e/79e6c5081a5197c4f4647db497fbd1e27f29714d/
  http://autobuild.buildroot.net/results/224/2242f8284aa4bdbb0ab959a6a6464f20fa043e2f/

Signed-off-by: Christophe Vu-Brugier <cvubrugier@yahoo.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/mdadm/mdadm.mk

@@ -11,7 +11,7 @@ MDADM_LICENSE = GPLv2+
 MDADM_LICENSE_FILES = COPYING
 
 MDADM_MAKE_OPT = \
-	CFLAGS="$(TARGET_CFLAGS)" CC="$(TARGET_CC)" -C $(MDADM_DIR) mdadm
+	CFLAGS="$(TARGET_CFLAGS)" CC="$(TARGET_CC)" CHECK_RUN_DIR=0 -C $(MDADM_DIR) mdadm
 
 MDADM_INSTALL_TARGET_OPT = \
 	DESTDIR=$(TARGET_DIR)/usr -C $(MDADM_DIR) install-mdadm