Merge branch 'sp/maint-http-enable-gzip' into maint

"git fetch" over http advertised that it supports "deflate", which
is much less common, and did not advertise more common "gzip" on its
Accept-Encoding header.

* sp/maint-http-enable-gzip:
  Enable info/refs gzip decompression in HTTP client

t/t5551-http-fetch.sh

@@ -32,13 +32,14 @@ setup_askpass_helper
 cat >exp <<EOF
 > GET /smart/repo.git/info/refs?service=git-upload-pack HTTP/1.1
 > Accept: */*
+> Accept-Encoding: gzip
 > Pragma: no-cache
 < HTTP/1.1 200 OK
 < Pragma: no-cache
 < Cache-Control: no-cache, max-age=0, must-revalidate
 < Content-Type: application/x-git-upload-pack-advertisement
 > POST /smart/repo.git/git-upload-pack HTTP/1.1
-> Accept-Encoding: deflate, gzip
+> Accept-Encoding: gzip
 > Content-Type: application/x-git-upload-pack-request
 > Accept: application/x-git-upload-pack-result
 > Content-Length: xxx