Make more fixes and improvements

- Fix Makefile flaking due to ZIPOBJ_FLAGS generation
- Make printf() floating point and gdtoa thread safe
- Polish up the runit / runitd programs some more
- Prune some more makefile dependencies

test/libc/str/longsort_test.c

@@ -19,6 +19,7 @@
 #include "libc/alg/alg.h"
 #include "libc/mem/mem.h"
 #include "libc/rand/rand.h"
+#include "libc/runtime/gc.internal.h"
 #include "libc/runtime/runtime.h"
 #include "libc/str/str.h"
 #include "libc/testlib/ezbench.h"

test/libc/str/pututf16_test.c

@@ -18,6 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/bits/bits.h"
 #include "libc/mem/mem.h"
+#include "libc/runtime/gc.internal.h"
 #include "libc/str/oldutf16.internal.h"
 #include "libc/str/str.h"
 #include "libc/testlib/testlib.h"