Fix adb shell in 7.0 tree

busybox sh does not seem to work properly in 7.0 trees so use
mksh for sh instead.

Change-Id: Ia33bc3894f929b1348c8714d4ddd00a2671c7e94

Android.mk

@@ -478,6 +478,9 @@ include $(CLEAR_VARS)
 # Create busybox symlinks... gzip and gunzip are excluded because those need to link to pigz instead
 BUSYBOX_LINKS := $(shell cat external/busybox/busybox-full.links)
 exclude := tune2fs mke2fs mkdosfs mkfs.vfat gzip gunzip
+ifeq ($(shell test $(PLATFORM_SDK_VERSION) -ge 24; echo $$?),0)
+    exclude += sh
+endif
 
 # Having /sbin/modprobe present on 32 bit devices with can cause a massive
 # performance problem if the kernel has CONFIG_MODULES=y