Change malloc/strdup/free to g_malloc/g_strdup/g_free in
util/envlist.c.
Remove NULL checks for pointers returned from g_malloc and g_strdup
as they exit in case of failure. Also, update calls to envlist_create
to reflect this.
Free array and array contents returned by envlist_to_environ using
g_free in bsd-user/main.c and linux-user/main.c.