Replace seq invocation with 'jot -'. They don't have seq on Mac by default.

Make sure on_asan_mac_host() always returns 1 on non-Darwin systems.

BUG=170629, 174873
TBR=thakis
Review URL: https://codereview.chromium.org/12256005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@182201 0039d316-1c4b-4281-b951-d872f2087c98

tools/clang/scripts/update.sh

@@ -87,6 +87,9 @@ done
 
 # Are we on a Chrome buildbot running ASan?
 function on_asan_mac_host {
+  if [[ "${OS}" != "Darwin" ]]; then
+    return 1
+  fi
   HOST="$(uname -n)"
   # Chrome Mac ASan Builder.
   if [[ "${HOST}" == "vm633-m1.golo.chromium.org" ]]; then
@@ -97,7 +100,7 @@ function on_asan_mac_host {
     return 0
   fi
   # mac_asan trybots.
-  for num in $(seq 600 655)
+  for num in $(jot - 600 655)
   do
     if [[ "${HOST}" == "vm${num}-m4.golo.chromium.org" ]]; then
       return 0