package/busybox: explicitly state binutils paths

We are not passing TARGET_CONFIGURE_OPTS when building busybox; instead
we are passing variables explicitly. As thus, it is missing the ar, nm,
and ranlib that we are using.

We add explicit AR, NM, and RANLIB, so that the ones we want to use
(i.e. the gcc-wrapped ones) are actually used.

Signed-off-by: Norbert Lange <nolange79@gmail.com>
[yann.morin.1998@free.fr:
  - reword the commit log to explain why we need that
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/busybox/busybox.mk

@@ -91,6 +91,9 @@ BUSYBOX_MAKE_ENV += \
 endif
 
 BUSYBOX_MAKE_OPTS = \
+	AR="$(TARGET_AR)" \
+	NM="$(TARGET_NM)" \
+	RANLIB="$(TARGET_RANLIB)" \
 	CC="$(TARGET_CC)" \
 	ARCH=$(KERNEL_ARCH) \
 	PREFIX="$(TARGET_DIR)" \