runtime: remove redundant explicit deref in trace.go

Replaces legacy Go syntax for pointer struct member access
with more modern auto-deref alternative.

Found using https://go-critic.github.io/overview#underef-ref

Change-Id: I71a3c424126c4ff5d89f9e4bacb6cc01c6fa2ddf
Reviewed-on: https://go-review.googlesource.com/122895
Run-TryBot: Iskander Sharipov <iskander.sharipov@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/runtime/trace.go

@@ -532,12 +532,12 @@ func traceEvent(ev byte, skip int, args ...uint64) {
 }
 
 func traceEventLocked(extraBytes int, mp *m, pid int32, bufp *traceBufPtr, ev byte, skip int, args ...uint64) {
-	buf := (*bufp).ptr()
+	buf := bufp.ptr()
 	// TODO: test on non-zero extraBytes param.
 	maxSize := 2 + 5*traceBytesPerNumber + extraBytes // event type, length, sequence, timestamp, stack id and two add params
 	if buf == nil || len(buf.arr)-buf.pos < maxSize {
 		buf = traceFlush(traceBufPtrOf(buf), pid).ptr()
-		(*bufp).set(buf)
+		bufp.set(buf)
 	}
 
 	ticks := uint64(cputicks()) / traceTickDiv
@@ -689,11 +689,11 @@ func traceString(bufp *traceBufPtr, pid int32, s string) (uint64, *traceBufPtr)
 	// so there must be no memory allocation or any activities
 	// that causes tracing after this point.
 
-	buf := (*bufp).ptr()
+	buf := bufp.ptr()
 	size := 1 + 2*traceBytesPerNumber + len(s)
 	if buf == nil || len(buf.arr)-buf.pos < size {
 		buf = traceFlush(traceBufPtrOf(buf), pid).ptr()
-		(*bufp).set(buf)
+		bufp.set(buf)
 	}
 	buf.byte(traceEvString)
 	buf.varint(id)
@@ -708,7 +708,7 @@ func traceString(bufp *traceBufPtr, pid int32, s string) (uint64, *traceBufPtr)
 	buf.varint(uint64(slen))
 	buf.pos += copy(buf.arr[buf.pos:], s[:slen])
 
-	(*bufp).set(buf)
+	bufp.set(buf)
 	return id, bufp
 }
 
@@ -1206,7 +1206,7 @@ func trace_userLog(id uint64, category, message string) {
 	traceEventLocked(extraSpace, mp, pid, bufp, traceEvUserLog, 3, id, categoryID)
 	// traceEventLocked reserved extra space for val and len(val)
 	// in buf, so buf now has room for the following.
-	buf := (*bufp).ptr()
+	buf := bufp.ptr()
 
 	// double-check the message and its length can fit.
 	// Otherwise, truncate the message.