Supply prototypes where possible. This uncovered type errors with

thread entrypoints:
(lwpSelect, shutdown_sequence): Parameters didn't match thread entry
point prototype.
(lwpEntryPoint): Arguments didn't match thread entry point prototype.

Change linkage of functions without prototype declaration to static
where possible.

Remove some superflous declarations, replace others by suitable
includes.

src/lib/update/distribute.c

@@ -45,14 +45,13 @@
 #include "update.h"
 #include "subs.h"
 #include "common.h"
+#include "prototypes.h"
 
 int
 dodistribute(struct sctstr *sp, int imex, s_char *path, double dist_i_cost,
 	     double dist_e_cost)
 	  /* import or export? */
 {
-    struct sctstr *getdistsp();
-    float distpathcost();
     struct ichrstr *ip;
     struct sctstr *dist;
     int amt;