Speed up lookup of "type_specific_data"

I noticed that "info locals" on a certain large Ada program was very
slow.  I tracked this down to ada_get_tsd_type expanding nearly every
CU in the program.

This patch fixes the problem by changing this code to use the more
efficient lookup_transparent_type which, unlike the Ada-specific
lookup functions, does not try to find all matching instances.

Note that I first tried fixing this by changing ada_find_any_type, but
this did not work -- I may revisit this approach at some later date.

Also note that the copyright dates on the test files are set that way
because I copied them from another test.

New in v2: the new test failed on the Linaro regression tester.
Looking at the logs, it seems that gdb was picking up a 'value' from
libgnat:

    $1 = {<text variable, no debug info>} 0xf7e227a4 <ada.calendar.formatting.value>

This version renames the local variable in an attempt to work around
this.

v3: In v2, while trying to reproduce the problem locally, I
accidentally forgot to commit one of the changes.

gdb/c-lang.c

@@ -935,9 +935,11 @@ public:
   }
 
   /* See language.h.  */
-  struct type *lookup_transparent_type (const char *name) const override
+  struct type *lookup_transparent_type (const char *name,
+					domain_search_flags flags)
+    const override
   {
-    return cp_lookup_transparent_type (name);
+    return cp_lookup_transparent_type (name, flags);
   }
 
   /* See language.h.  */