Fix an edge case when obtaining home directory.

Make the path to home directory empty before calling get_home_dir(), otherwise if the call fails, the contents are undefined.

src/autocomplete.c

@@ -210,6 +210,7 @@ static void complt_home_dir(ToxWindow *self, char *path, int pathsize, const cha
     ChatContext *ctx = self->chatwin;
 
     char homedir[MAX_STR_SIZE];
+    homedir[0] = '\0';
     get_home_dir(homedir, sizeof(homedir));
 
     char newline[MAX_STR_SIZE];

src/configdir.c

@@ -67,6 +67,7 @@ void get_home_dir(char *home, int size)
 char *get_user_config_dir(void)
 {
     char home[NSS_BUFLEN_PASSWD];
+    home[0] = '\0';
     get_home_dir(home, sizeof(home));
 
     char *user_config_dir;