Initialize testsuite count in global scope.

Summary:
Python 3.8+ can't resolve `count` as a global if it isn't declared
in global scope.
Explicitly initialize it in global scope to fix the script.

Reviewed By: dulinriley

Differential Revision: D23400931

fbshipit-source-id: 66906d0148b4b6565e18bc388112bd8229baf203

utils/testsuite/testsuite.py

@@ -335,6 +335,7 @@ def printVerbose(s):
 istty = sys.stdout.isatty()
 completed = Value("i", 0)
 ttyWidth = os.get_terminal_size().columns if istty else 0
+count = -1
 
 
 def showStatus(filename):