update-tzdata.py needs to know where to find icu.

Change-Id: If5561b92c233276fb072da62be21f23df4781c41
diff --git a/libc/tools/zoneinfo/update-tzdata.py b/libc/tools/zoneinfo/update-tzdata.py
index 3dcb210..6b69a5a 100755
--- a/libc/tools/zoneinfo/update-tzdata.py
+++ b/libc/tools/zoneinfo/update-tzdata.py
@@ -31,8 +31,8 @@
 print 'Found bionic in %s ...' % bionic_dir
 
 # Find the icu4c directory.
-icu_dir = os.path.realpath('%s/../external/icu4c' % bionic_dir)
-CheckDirExists(icu_dir, 'external/icu4c')
+icu_dir = os.path.realpath('%s/../external/icu/icu4c/source' % bionic_dir)
+CheckDirExists(icu_dir, 'external/icu/icu4c/source')
 print 'Found icu in %s ...' % icu_dir