Change gdbarch_inner_than to return bool

A recent patch from Andrew pointed out that gdbarch_inner_than returns
'int', while it should really return 'bool'.

Approved-By: Pedro Alves <pedro@palves.net>

gdb/gdbarch_components.py

@@ -1020,7 +1020,7 @@ is not used.
 )
 
 Function(
-    type="int",
+    type="bool",
     name="inner_than",
     params=[("CORE_ADDR", "lhs"), ("CORE_ADDR", "rhs")],
 )