Add "fastboot --version".

So bug reporters can actually tell us what they're running.

Bug: http://b/21583225
Change-Id: If2a4ae97b4792aa321566603ce2c354a72d32307
diff --git a/fastboot/Android.mk b/fastboot/Android.mk
index dee471a..1808042 100644
--- a/fastboot/Android.mk
+++ b/fastboot/Android.mk
@@ -14,6 +14,8 @@
 
 LOCAL_PATH:= $(call my-dir)
 
+fastboot_version := $(shell git -C $(LOCAL_PATH) rev-parse --short=12 HEAD 2>/dev/null)-android
+
 include $(CLEAR_VARS)
 
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/../mkbootimg \
@@ -25,14 +27,15 @@
 LOCAL_CONLYFLAGS += -std=gnu99
 LOCAL_CFLAGS += -Wall -Wextra -Werror
 
+LOCAL_CFLAGS += -DFASTBOOT_REVISION='"$(fastboot_version)"'
+
 ifeq ($(HOST_OS),linux)
   LOCAL_SRC_FILES += usb_linux.c util_linux.c
 endif
 
 ifeq ($(HOST_OS),darwin)
   LOCAL_SRC_FILES += usb_osx.c util_osx.c
-  LOCAL_LDLIBS += -lpthread -framework CoreFoundation -framework IOKit \
-	-framework Carbon
+  LOCAL_LDLIBS += -lpthread -framework CoreFoundation -framework IOKit -framework Carbon
   LOCAL_CFLAGS += -Wno-unused-parameter
 endif