Avoid checking if a function uses itself as function pointer

Fixes #206

The sample code from the issue provided a smart way to cheat the dumb FP parser.
In fact, the & is referred to the return type (correct) but the comparator doesn't know about semantics and simply prepends the ampersand before searching for the match.
So the code matches itself, which makes absolutely no sense.
Avoiding this occurrence fixes the issue, however the entire code for prototype line insertion should be refactored in a saner way (see #180 and #191 for another problem)

Author: facchinm

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

@@ -56,32 +56,32 @@ func (p *CTagsParser) findLineWhereToInsertPrototypes() int {
 }
 
 func (p *CTagsParser) firstFunctionPointerUsedAsArgument() int {
-	functionNames := p.collectFunctionNames()
+	functionTags := p.collectFunctions()
 	for _, tag := range p.tags {
-		if functionNameUsedAsFunctionPointerIn(tag, functionNames) {
+		if functionNameUsedAsFunctionPointerIn(tag, functionTags) {
 			return tag.Line
 		}
 	}
 	return -1
 }
 
-func functionNameUsedAsFunctionPointerIn(tag *types.CTag, functionNames []string) bool {
-	for _, functionName := range functionNames {
-		if strings.Index(tag.Code, "&"+functionName) != -1 {
+func functionNameUsedAsFunctionPointerIn(tag *types.CTag, functionTags []*types.CTag) bool {
+	for _, functionTag := range functionTags {
+		if tag.Line != functionTag.Line && strings.Index(tag.Code, "&"+functionTag.FunctionName) != -1 {
 			return true
 		}
 	}
 	return false
 }
 
-func (p *CTagsParser) collectFunctionNames() []string {
-	names := []string{}
+func (p *CTagsParser) collectFunctions() []*types.CTag {
+	functionTags := []*types.CTag{}
 	for _, tag := range p.tags {
 		if tag.Kind == KIND_FUNCTION {
-			names = append(names, tag.FunctionName)
+			functionTags = append(functionTags, tag)
 		}
 	}
-	return names
+	return functionTags
 }
 
 func (p *CTagsParser) firstFunctionAtLine() int {