Fixed uninitialized pointer free (usrsub[i] and usrdir[i]) if a message group...

Fixed uninitialized pointer free (usrsub[i] and usrdir[i]) if a message group or library is configured by no sub-boards or directories are configured.

src/sbbs3/main.cpp

@@ -1716,7 +1716,7 @@ bool sbbs_t::init()
 			return(false);
 		}
 
-		if((usrsub=(uint **)MALLOC(sizeof(uint *)*cfg.total_grps))==NULL) {
+		if((usrsub=(uint **)calloc(cfg.total_grps,sizeof(uint *)))==NULL) {
 			errormsg(WHERE, ERR_ALLOC, "usrsub", sizeof(uint)*cfg.total_grps);
 			return(false);
 		}
@@ -1784,7 +1784,7 @@ bool sbbs_t::init()
 			return(false);
 		}
 
-		if((usrdir=(uint **)MALLOC(sizeof(uint *)*cfg.total_libs))==NULL) {
+		if((usrdir=(uint **)calloc(cfg.total_libs,sizeof(uint *)))==NULL) {
 			errormsg(WHERE, ERR_ALLOC, "usrdir", sizeof(uint)*cfg.total_libs);
 			return(false);
 		}