read conmon output and convert to json in two steps

when reading the output from conmon using the JSON methods, it appears that
JSON marshalling is higher in pprof than it really is because the pipe is
"waiting" for a response. this gives us a clearer look at the real CPU/time
consumers.

Signed-off-by: baude <bbaude@redhat.com>

libpod/oci.go

@@ -1,6 +1,7 @@
 package libpod
 
 import (
+	"bufio"
 	"bytes"
 	"encoding/json"
 	"fmt"
@@ -418,7 +419,12 @@ func (r *OCIRuntime) createOCIContainer(ctr *Container, cgroupParent string, res
 	ch := make(chan syncStruct)
 	go func() {
 		var si *syncInfo
-		if err = json.NewDecoder(parentPipe).Decode(&si); err != nil {
+		rdr := bufio.NewReader(parentPipe)
+		b, err := rdr.ReadBytes('\n')
+		if err != nil {
+			ch <- syncStruct{err: err}
+		}
+		if err := json.Unmarshal(b, &si); err != nil {
 			ch <- syncStruct{err: err}
 			return
 		}