SERVER: Fix for 64-bit save-game files

Ensure all "" references are set to string ref 0 (should fix
  any affected save-game files)
Looks like dimman's previous fix for 64-bit load/save
  (QW-Group@21b5ddc)
  didn't ever make it into mvdsv, so was removed again
  during sync to 3.1 - this led to extra fields being written
  out that didn't need to be included.

Fixes QW-Group#297

pr_edict.c

@@ -43,16 +43,15 @@ static int pr_globaloffsetpatch_nq[62] = {0,0,0,0,0,666,-4,-4,8,8,
 8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8, 8,8};
 #endif
 
-int		type_size[8] =
-{
+int	type_size[8] = {
 	1,					// void
-	sizeof(void *)/4,	// string_t
+	1,	                // string_t
 	1,					// float
 	3,					// vector
 	1,					// entity
 	1,					// field
-	sizeof(void *)/4, 	// func_t
-	sizeof(void *)/4 	// pointer (its an int index)
+	1,              	// func_t
+	1 	                // pointer (its an int index)
 };
 
 ddef_t *ED_FieldAtOfs (int ofs);

pr_exec.c

@@ -700,6 +700,11 @@ void PR1_SetString(string_t* address, char* s)
 		return;
 	}
 
+	if (!s || !s[0]) {
+		*address = 0;
+		return;
+	}
+
 	if (s - pr_strings < 0) {
 		for (i = 0; i < num_prstr; i++) {
 			if (pr_strtbl[i] == s) {