local: fix memory leak when putting together locale settings

Also, we need to use proper strv_env_xyz() calls when putting together
the environment array, since otherwise settings won't be properly
overriden.

And let's get rid of strv_appendf(), is overkill and there was only one
user.

src/shared/strv.c

@@ -424,21 +424,6 @@ fail:
         return NULL;
 }
 
-char **strv_appendf(char **l, const char *format, ...) {
-        va_list ap;
-        _cleanup_free_ char *s = NULL;
-        int r;
-
-        va_start(ap, format);
-        r = vasprintf(&s, format, ap);
-        va_end(ap);
-
-        if (r < 0)
-                return NULL;
-
-        return strv_append(l, s);
-}
-
 int strv_push(char ***l, char *value) {
         char **c;
         unsigned n;

src/shared/strv.h

@@ -42,7 +42,6 @@ unsigned strv_length(char * const *l) _pure_;
 char **strv_merge(char **a, char **b);
 char **strv_merge_concat(char **a, char **b, const char *suffix);
 char **strv_append(char **l, const char *s);
-char **strv_appendf(char **l, const char *format, ...) _printf_attr_(2, 3);
 int strv_extend(char ***l, const char *value);
 int strv_push(char ***l, char *value);