Handle more cases when searching for callback reference

the tag will be searched only if its signature is void and it's not being skipped for other reasons

src/arduino.cc/builder/ctags/ctags_parser.go

@@ -236,7 +236,6 @@ func parseTag(row string) *types.CTag {
 
 	parts = parts[2:]
 
-	signature := ""
 	returntype := ""
 	for _, part := range parts {
 		if strings.Contains(part, ":") {
@@ -253,7 +252,7 @@ func parseTag(row string) *types.CTag {
 			case "typeref":
 				tag.Typeref = value
 			case "signature":
-				signature = value
+				tag.Signature = value
 			case "returntype":
 				returntype = value
 			case "class":
@@ -265,7 +264,7 @@ func parseTag(row string) *types.CTag {
 			}
 		}
 	}
-	tag.Prototype = returntype + " " + tag.FunctionName + signature + ";"
+	tag.Prototype = returntype + " " + tag.FunctionName + tag.Signature + ";"
 
 	if strings.Contains(row, "/^") && strings.Contains(row, "$/;") {
 		tag.Code = row[strings.Index(row, "/^")+2 : strings.Index(row, "$/;")]

src/arduino.cc/builder/ctags/ctags_to_prototypes.go

@@ -70,6 +70,9 @@ func functionNameUsedAsFunctionPointerIn(tag *types.CTag, functionNames []string
 		if strings.Index(tag.Code, "&"+functionName) != -1 {
 			return true
 		}
+		if strings.Index(tag.Code, functionName) != -1 {
+			return true
+		}
 	}
 	return false
 }

src/arduino.cc/builder/types/types.go

@@ -252,6 +252,7 @@ type CTag struct {
 	Filename     string
 	Typeref      string
 	SkipMe       bool
+	Signature    string
 
 	Prototype          string
 	Function           string