Corrected some GCC 7.1+ compile warnings (#3522)

* Fixes #2787 and fixes #3513.
* Resolved some format-truncation warnings.
* The remaining will be fixed at a later time.
Thanks to @RadianFord and @Lemongrass3110!

src/common/utils.cpp

@@ -216,7 +216,7 @@ void findfile(const char *p, const char *pat, void (func)(const char*))
 	DIR* dir;					// pointer to the scanned directory.
 	struct dirent* entry;		// pointer to one directory entry.
 	struct stat dir_stat;       // used by stat().
-	char tmppath[MAX_DIR_PATH+1];
+	char tmppath[MAX_DIR_PATH * 2];
 	char path[MAX_DIR_PATH+1]= ".";
 	const char *pattern = (pat==NULL)? "" : pat;
 	if(p!=NULL) strcpy(path,p);