sys/acct.h: Add sys/types.h include

There's no harm in including sys/types.h here and acct.h needs it. This
file isn't defined by any standard, so what we do here wrt namespaces
likely doesn't matter. If it does, it will be easy enough to add the
necessary __BSD_VISIBLE guards in the future.

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sys/sys/acct.h

@@ -42,6 +42,8 @@
 
 #ifdef _KERNEL
 #define float uint32_t
+#else
+#include <sys/types.h>
 #endif
 
 #define AC_COMM_LEN 16