Python: fix print statements in stack.py

No change to logic. This fixes an issue introduced in
https://crrev.com/c/3065476. That CL converted all python2 print
statements to use parentheses, however `print()` will literally print
`()` (it's a print statement with an empty tuple as an argument). As a
quick fix, import the actual print_function to get the correct behavior.
This will have no effect on python3 since the print function is builtin.

Bug: 1223892
Test: third_party/android_platform/development/scripts/stack --help
Change-Id: I1e2e7eb58c77b7ab4449e28932ff05a9b3598a8b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3200060
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Auto-Submit: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/main@{#927499}
NOKEYCHECK=True
GitOrigin-RevId: c08a1ab3b27b48e2664003abf2a62ba89d291d3b
diff --git a/development/scripts/stack.py b/development/scripts/stack.py
index ccf1f47..bcd1685 100755
--- a/development/scripts/stack.py
+++ b/development/scripts/stack.py
@@ -16,6 +16,8 @@
 
 """stack symbolizes native crash dumps."""
 
+from __future__ import print_function
+
 import getopt
 import glob
 import logging