basic: make check-pointer-deref clean

Add the needed assert changes to make the code clean
for the new check-pointer-deref script.

Note that for `_cmp()` functions its a bit of a question
if we want `assert()` or `POINTER_MAY_BE_NULL()` here. The
former is more correct but it adds a (small) runtime hit. If
we use POINTER_MAY_BE_NULL() it is compiled out but strictly
speaking it is wrong (so at least we would need a comment).

src/basic/strv.c

@@ -587,6 +587,9 @@ int strv_push_with_size(char ***l, size_t *n, char *value) {
          * If n is not NULL, the size after the push will be returned.
          * If value is empty, no action is taken and *n is not set. */
 
+        assert(l);
+        POINTER_MAY_BE_NULL(n);
+
         if (!value)
                 return 0;
 
@@ -615,6 +618,8 @@ int strv_push_pair(char ***l, char *a, char *b) {
         char **c;
         size_t n;
 
+        assert(l);
+
         if (!a && !b)
                 return 0;
 
@@ -828,6 +833,9 @@ char** strv_remove(char **l, const char *s) {
 }
 
 bool strv_overlap(char * const *a, char * const *b) {
+        POINTER_MAY_BE_NULL(a);
+        POINTER_MAY_BE_NULL(b);
+
         STRV_FOREACH(i, a)
                 if (strv_contains(b, *i))
                         return true;
@@ -836,6 +844,9 @@ bool strv_overlap(char * const *a, char * const *b) {
 }
 
 static int str_compare(char * const *a, char * const *b) {
+        assert(a);
+        assert(b);
+
         return strcmp(*a, *b);
 }
 
@@ -862,6 +873,9 @@ char** strv_sort_uniq(char **l) {
 int strv_compare(char * const *a, char * const *b) {
         int r;
 
+        POINTER_MAY_BE_NULL(a);
+        POINTER_MAY_BE_NULL(b);
+
         if (strv_isempty(a)) {
                 if (strv_isempty(b))
                         return 0;