Test

SrsRtcTcpConn: use read instead of read_fully. #272

Job	Run time
cygwin64-cache	4m 18s
multiple-arch-aarch64	7m 44s
multiple-arch-armv7	8m 27s
utest-regression-blackbox-test	6m 57s
cygwin64	8m 21s
fast	2s
build-ubuntu18	2m 20s
build-cross-arm	3m 38s
build-centos7	3m 31s
build-ubuntu16	3m 11s
build-ubuntu20	2m 30s
build-cross-aarch64	3m 23s
coverage	3m 19s
multiple-arch-amd64	2m 3s
test-done	2s
	59m 46s

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