[verify_sdk_api] Use abspath in the cp command

... so the command works anywhere. The args are relative to build out
dir, and users are very unlikely to run commands from there.

Fixed: 81541

Change-Id: Ib01e66759257bd0cdc30eb2221c771fbfbfdf3e5
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/560901
Reviewed-by: Rich Kadel <richkadel@google.com>
Commit-Queue: Jay Zhuang <jayzhuang@google.com>
diff --git a/build/sdk/verify_sdk_api.py b/build/sdk/verify_sdk_api.py
index 778c2d89..f8f6bad 100755
--- a/build/sdk/verify_sdk_api.py
+++ b/build/sdk/verify_sdk_api.py
@@ -5,6 +5,7 @@
 
 import argparse
 import json
+import os
 import platform
 import sys
 
@@ -73,7 +74,9 @@
         type = 'Warning' if args.warn else 'Error'
         print('%s: SDK contents have changed!' % type)
         print('Please acknowledge this change by running:')
-        print('  cp ' + args.updated + ' ' + args.reference)
+        print(
+            '  cp ' + os.path.abspath(args.updated) + ' ' +
+            os.path.abspath(args.reference))
         if not args.warn:
             return 1