gclient: Don't try opening pseudo-terminal pipes on AIX

Change-Id: I57228d5b9d15253ae525cb2d138bfa9e73fea0e3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2416977
Reviewed-by: Dirk Pranke <dpranke@google.com>
Commit-Queue: Dirk Pranke <dpranke@google.com>

gclient_utils.py

@@ -589,7 +589,8 @@ def CheckCallAndFilter(args, print_stdout=False, filter_fn=None,
     # If our stdout is a terminal, then pass in a psuedo-tty pipe to our
     # subprocess when filtering its output. This makes the subproc believe
     # it was launched from a terminal, which will preserve ANSI color codes.
-    if sys.stdout.isatty() and GetMacWinAixOrLinux() != 'win':
+    os_type = GetMacWinAixOrLinux()
+    if sys.stdout.isatty() and os_type != 'win' and os_type != 'aix':
       pipe_reader, pipe_writer = os.openpty()
     else:
       pipe_reader, pipe_writer = os.pipe()