* gdb.c++/derivation.exp, gdb.c++/overload.exp,

gdb.c++/userdef.cc: Place comments on the lines to which the
marker function might return.
* gdb.c++/derivation.exp, gdb.c++/overload.exp,
gdb.c++/userdef.exp: Look for those comments to check that we've
returned to the right place, instead of checking line numbers.

gdb/testsuite/gdb.c++/derivation.cc

@@ -214,9 +214,9 @@ int main(void)
     #endif
     
 
-    marker1();
+    marker1(); // marker1-returns-here
     
-    a_instance.a = 20;
+    a_instance.a = 20; // marker1-returns-here
     a_instance.aa = 21;
     b_instance.b = 22;
     b_instance.bb = 23;