Add "fastboot --version".

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

Bug: http://b/21583225
Change-Id: If2a4ae97b4792aa321566603ce2c354a72d32307

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_MODULE_TAGS := debug
 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
 

fastboot/fastboot.cpp

@@ -971,8 +971,9 @@ int main(int argc, char **argv)
         {"page_size", required_argument, 0, 'n'},
         {"ramdisk_offset", required_argument, 0, 'r'},
         {"tags_offset", required_argument, 0, 't'},
-        {"help", 0, 0, 'h'},
-        {"unbuffered", 0, 0, 0},
+        {"help", no_argument, 0, 'h'},
+        {"unbuffered", no_argument, 0, 0},
+        {"version", no_argument, 0, 0},
         {0, 0, 0, 0}
     };
 
@@ -1044,6 +1045,9 @@ int main(int argc, char **argv)
             if (strcmp("unbuffered", longopts[longindex].name) == 0) {
                 setvbuf(stdout, NULL, _IONBF, 0);
                 setvbuf(stderr, NULL, _IONBF, 0);
+            } else if (strcmp("version", longopts[longindex].name) == 0) {
+                fprintf(stdout, "fastboot version %s\n", FASTBOOT_REVISION);
+                return 0;
             }
             break;
         default: