bpo-34898: Add mtime parameter to gzip.compress(). (GH-9704)

Without setting mtime, time.time() will be used as the timestamp which will
end up in the compressed data and each invocation of the compress() function
will vary over time.
diff --git a/Misc/ACKS b/Misc/ACKS
index 89fb0c7..aba6094 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1615,6 +1615,7 @@
 Anatoly Techtonik
 Martin Teichmann
 Gustavo Temple
+Guo Ci Teo
 Mikhail Terekhov
 Victor Terrón
 Pablo Galindo
diff --git a/Misc/NEWS.d/next/Library/2018-10-04-17-23-43.bpo-34898.Wo2PoJ.rst b/Misc/NEWS.d/next/Library/2018-10-04-17-23-43.bpo-34898.Wo2PoJ.rst
new file mode 100644
index 0000000..4c0a061
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-10-04-17-23-43.bpo-34898.Wo2PoJ.rst
@@ -0,0 +1,2 @@
+Add `mtime` argument to `gzip.compress` for reproducible output.
+Patch by Guo Ci Teo.
\ No newline at end of file