Rename exclusions.txt in the script

The file name has been changed in a previous CL

Test: run the script
Change-Id: I7cc1b183989ae674e14e65321e09c51d5c689ad0

Author: Po-Chien Hsueh

tools/repo_diff/repo_diff_android.py

@@ -24,7 +24,7 @@
 DEFAULT_UPSTREAM_MANIFEST_URL = "https://android.googlesource.com/platform/manifest"
 DEFAULT_UPSTREAM_MANIFEST_BRANCH = "android-8.0.0_r1"
 SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
-DEFAULT_EXCLUSIONS_FILE = os.path.join(SCRIPT_DIR, "exclusions.txt")
+DEFAULT_EXCLUSIONS_FILE = os.path.join(SCRIPT_DIR, "android_exclusions.txt")
 
 
 def parse_args():