selector.EpollSelector: add new parameter to support EPOLLEXCLUSIVE

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2018-12-17.10:31:38.448>
labels = ['3.8', 'type-feature', 'library']
title = 'selector.EpollSelector: add new parameter to support EPOLLEXCLUSIVE'
updated_at = <Date 2019-01-30.14:43:45.137>
user = 'https://github.com/Zheaoli'

bugs.python.org fields:

activity = <Date 2019-01-30.14:43:45.137>
actor = 'Manjusaka'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2018-12-17.10:31:38.448>
creator = 'Manjusaka'
dependencies = []
files = []
hgrepos = []
issue_num = 35517
keywords = ['patch']
message_count = 20.0
messages = ['331969', '331970', '331971', '331972', '331973', '331974', '331977', '331979', '331991', '331994', '331996', '331998', '331999', '332000', '332017', '332018', '332019', '332038', '332039', '334562']
nosy_count = 6.0
nosy_names = ['vstinner', 'giampaolo.rodola', 'neologix', 'yselivanov', 'xiang.zhang', 'Manjusaka']
pr_nums = ['11193']
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue35517'
versions = ['Python 3.8']