tree-wide: replace strv_split_full() with strv_split_extract() everywhere

Behaviour is not identical, as shown by the tests in test-strv.
The combination of EXTRACT_UNQUOTE without EXTRACT_RELAX only appears in
the test, so it doesn't seem particularly important. OTOH, the difference
in handling of squished parameters could make a difference. New behaviour
is what both bash and python do, so I think we can ignore this corner case.

This change has the following advantages:
- the duplication of code paths that do a very similar thing is removed
- extract_one_word() / strv_split_extract() return a proper error code.

src/basic/strv.c

@@ -256,44 +256,6 @@ int strv_extend_strv_concat(char ***a, char * const *b, const char *suffix) {
         return 0;
 }
 
-char **strv_split_full(const char *s, const char *separator, SplitFlags flags) {
-        const char *word, *state;
-        size_t l;
-        size_t n, i;
-        char **r;
-
-        assert(s);
-
-        if (!separator)
-                separator = WHITESPACE;
-
-        s += strspn(s, separator);
-        if (isempty(s))
-                return new0(char*, 1);
-
-        n = 0;
-        _FOREACH_WORD(word, l, s, separator, flags, state)
-                n++;
-
-        r = new(char*, n+1);
-        if (!r)
-                return NULL;
-
-        i = 0;
-        _FOREACH_WORD(word, l, s, separator, flags, state) {
-                r[i] = strndup(word, l);
-                if (!r[i]) {
-                        strv_free(r);
-                        return NULL;
-                }
-
-                i++;
-        }
-
-        r[i] = NULL;
-        return r;
-}
-
 char **strv_split_newlines(const char *s) {
         char **l;
         size_t n;

src/basic/strv.h

@@ -72,13 +72,19 @@ static inline bool strv_isempty(char * const *l) {
         return !l || !*l;
 }
 
-char **strv_split_full(const char *s, const char *separator, SplitFlags flags);
-static inline char **strv_split(const char *s, const char *separator) {
-        return strv_split_full(s, separator, 0);
-}
 char **strv_split_newlines(const char *s);
 
 int strv_split_extract(char ***t, const char *s, const char *separators, ExtractFlags flags);
+static inline char **strv_split(const char *s, const char *separators) {
+        char **ret;
+        int r;
+
+        r = strv_split_extract(&ret, s, separators, 0);
+        if (r < 0)
+                return NULL;
+
+        return ret;
+}
 
 /* Given a string containing white-space separated tuples of words themselves separated by ':',
  * returns a vector of strings. If the second element in a tuple is missing, the corresponding