static inline C functions (mingw's printf and time), macOS libraries that call their host, lld's missing-library message

- a static inline function in a header is called through a pointer a small C file keeps
  (void *finch_inl_f = &f), built with the program's include folders and cached
- --shared on macOS links with -undefined dynamic_lookup, as a .so does on Linux
- "unable to find library -lx" (lld, MinGW) gives the library-not-found advice
- the language server test shows the index records when alias completion fails

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016GzNP6r8dg6WDxUVZy8wjL

tests/new/cunion.h

@@ -36,3 +36,6 @@ static inline int fill_key(Event *e, int key) {
     return 1;
 }
 int poll_event(Event *e);
+
+static inline int twice(int x) { return 2 * x; }
+static inline int sum_all(int n, ...) { return n; }