Define __USE_TIME_BITS64 when it is necessary.

Glibc and musl both defines this macro.
Glibc defines it for 64-bit time_t on 32-bit arch
and for 64-bit architectures.

Signed-off-by: Dmitry Chestnykh <dm.chestnykh@gmail.com>

include/features.h

@@ -437,4 +437,8 @@
 # include <libc-internal.h>
 #endif
 
+#if defined(__UCLIBC_USE_TIME64__) || __TARGET_ARCH_BITS__ == 64
+#define __USE_TIME_BITS64 1
+#endif
+
 #endif	/* features.h  */