Add adb's ANDROID_SERIAL to fastboot too.
We noticed this when trying to script on-device testing for the dalvik
continuous build.
Also fix a typo in adb's help.
diff --git a/adb/commandline.c b/adb/commandline.c
index 411bb82..f41146b 100644
--- a/adb/commandline.c
+++ b/adb/commandline.c
@@ -97,7 +97,7 @@
" returns an error if more than one emulator is running.\n"
" -s <serial number> - directs command to the USB device or emulator with\n"
" the given serial number. Overrides ANDROID_SERIAL\n"
- " envivornment variable.\n"
+ " environment variable.\n"
" -p <product name or path> - simple product name like 'sooner', or\n"
" a relative/absolute path to a product\n"
" out directory like 'out/target/product/sooner'.\n"