Removes several times warning C4018 in MSVC.

* Removes signed/unsigned mismatch warning.

include/express/hash.h

@@ -144,8 +144,8 @@ typedef struct Hash_Table_ {
 } * Hash_Table;
 
 typedef struct {
-    int i;  /* segment index (i think) */
-    int j;  /* key index in segment (ditto) */
+    unsigned int i;  /* segment index (i think) */
+    unsigned int j;  /* key index in segment (ditto) */
     Element p;  /* usually the next element to be returned */
     Hash_Table table;
     char type;

src/clutils/scl_hash.cc

@@ -208,7 +208,7 @@ HASHlist( HashEntry * he ) {
 
 void
 HASHdestroy( Hash_TableP table ) {
-    int     i, j;
+    unsigned int i, j;
     struct Element ** s;
     struct Element * p, *q;
 

src/clutils/scl_hash.h

@@ -116,8 +116,8 @@ struct Hash_Table {
 };
 
 typedef struct {
-    int i;                  // segment index (i think)
-    int j;                  // key index in segment (ditto)
+    unsigned int i;         // segment index (i think)
+    unsigned int j;         // key index in segment (ditto)
     struct Element * p;     // usually the next element to be returned
     struct Hash_Table * table;
     char type;

src/express/hash.c

@@ -276,7 +276,7 @@ HASH_in_use( Hash_Table table, char * action ) {
 
 void
 HASHdestroy( Hash_Table table ) {
-    int     i, j;
+    unsigned int i, j;
     Segment s;
     Element p, q;
 
@@ -533,7 +533,7 @@ HASHcopy( Hash_Table oldtable ) {
     Segment s, s2;
     Element * pp;   /* old element */
     Element * qq;   /* new element */
-    int i, j;
+    unsigned int i, j;
 
     newtable = HASH_Table_new();
     for( i = 0; i < oldtable->SegmentCount; i++ ) {