Fix warnings.

src/engine/debugger.cpp

@@ -2691,7 +2691,7 @@ static int process_command( char * line )
             *iter++ = '\0';
         }
     }
-    result = run_command( tokens.size(), const_cast<const char **>( &tokens[0] ) );
+    result = run_command( (int) tokens.size(), const_cast<const char **>( &tokens[0] ) );
     return result;
 }
 

src/engine/execnt.cpp

@@ -1291,6 +1291,7 @@ static int32_t get_free_cmdtab_slot()
             return slot;
     err_printf( "no slots for child!\n" );
     b2::clean_exit( EXITBAD );
+    return -1;
 }