Enable GUI support for Sublime Text build command

exec.py

class AsyncProcess(object):
    def __init__(self, arg_list, env, listener,
    
        # .... (removed) code
        
        # Hide the console window on Windows
        startupinfo = None
        if os.name == "nt":
            startupinfo = subprocess.STARTUPINFO()
            # comment line below to enable GUI processes
            startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW