Update version number to 3.7.1 (protocolbuffers#5947)

* Update version number to 3.7.1

* Update version number in port_def.inc

Update version number to 3.7.0 (protocolbuffers#5793)

* Update version number to 3.7.0

* Add php/releash.sh to Makefile.am

* Make cpp_distcheck exit on fail

Merge pull request protocolbuffers#5766 from TeBoring/3.7.x-fix

Update version number to 3.7.0rc3

Protocol Buffers v3.7.0rc2

Fixed infinite recursion problem with Java GeneratedMessageV3 (protoc…

…olbuffers#5657)

GeneratedMessageV3#setUnknownFieldsProto3 was trying to delegate to
setUnknownFields but was inadvertently resulting in infinite recursion.
This commit makes setUnknownFields and setUnknownFieldsProto3 delegate
to a common private method to fix the problem and avoid confusion.

Merge pull request protocolbuffers#5644 from TeBoring/fix-4765

Convert integer to string if field is string field in json

Protocol Buffers v3.6.1.3

Protocol Buffers v3.6.1.2

Protocol Buffers v3.6.1.1

Added conformance tests to Bazel BUIDL file.