Log x-amz-request-id as log and XML error response (#6173)

Currently, requestid field in logEntry is not populated, as the
requestid field gets set at the very end.
It is now set before regular handler functions. This is also
useful in setting it as part of the XML error response.

Travis build for ppc64le has been quite inconsistent and stays queued
for most of the time. Removing this build as part of Travis.yml for
the time being.

cmd/utils.go

@@ -331,7 +331,7 @@ func ceilFrac(numerator, denominator int64) (ceil int64) {
 }
 
 // Returns context with ReqInfo details set in the context.
-func newContext(r *http.Request, api string) context.Context {
+func newContext(r *http.Request, w http.ResponseWriter, api string) context.Context {
 	vars := mux.Vars(r)
 	bucket := vars["bucket"]
 	object := vars["object"]
@@ -341,6 +341,7 @@ func newContext(r *http.Request, api string) context.Context {
 		object = prefix
 	}
 	reqInfo := &logger.ReqInfo{
+		RequestID:  w.Header().Get(responseRequestIDKey),
 		RemoteHost: handlers.GetSourceIP(r),
 		UserAgent:  r.Header.Get("user-agent"),
 		API:        api,