[perl #92906] perl -d has non-functional b command

This fixes a regression introduced after 5.14.0.

Commit 6f83ef0 got dbfile and dbline magic mixed up and ended up
apply set-magic to the hash (dbfile), not to the element (dbline).

The result was that debugger breakpoints simply did not work at all.

mg_raw.h

@@ -50,9 +50,9 @@
       "/* isaelem 'i' @ISA array element */" },
     { 'k', "want_vtbl_nkeys | PERL_MAGIC_VALUE_MAGIC",
       "/* nkeys 'k' scalar(keys()) lvalue */" },
-    { 'L', "want_vtbl_dbline",
+    { 'L', "magic_vtable_max",
       "/* dbfile 'L' Debugger %_<filename */" },
-    { 'l', "magic_vtable_max",
+    { 'l', "want_vtbl_dbline",
       "/* dbline 'l' Debugger %_<filename element */" },
     { 'o', "want_vtbl_collxfrm | PERL_MAGIC_VALUE_MAGIC",
       "/* collxfrm 'o' Locale transformation */" },

regen/mg_vtable.pl

@@ -53,9 +53,10 @@ BEGIN
 		  desc => '@ISA array element' },
      nkeys => { char => 'k', vtable => 'nkeys', value_magic => 1,
 		desc => 'scalar(keys()) lvalue' },
-     dbfile => { char => 'L', vtable => 'dbline',
+     dbfile => { char => 'L',
 		 desc => 'Debugger %_<filename' },
-     dbline => { char => 'l', desc => 'Debugger %_<filename element' },
+     dbline => { char => 'l', vtable => 'dbline',
+		 desc => 'Debugger %_<filename element' },
      shared => { char => 'N', desc => 'Shared between threads',
 		 unknown_to_sv_magic => 1 },
      shared_scalar => { char => 'n', desc => 'Shared between threads',