[python/Ada] gdb.lookup_type fails to looking primitive type

The following change...

    commit 1994afbf19
    Date:   Tue Dec 23 07:55:39 2014 -0800
    Subject: Look up primitive types as symbols.

... caused the following regression:

    % gdb
    (gdb) set lang ada
    (gdb) python print gdb.lookup_type('character')
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
    gdb.error: No type named character.
    Error while executing Python code.

This is because the language_lookup_primitive_type_as_symbol call
was moved to the la_lookup_symbol_nonlocal hook. A couple of
implementations have been upated accordingly, but the Ada version
has not. This patch fixes this omission.

gdb/ChangeLog:

        * ada-lang.c (ada_lookup_symbol_nonlocal): If name not found
        in static block, then try searching for primitive types.

gdb/testsuite/ChangeLog:

        * gdb.python/py-lookup-type.exp: New file.

gdb/testsuite/gdb.python/py-lookup-type.exp

@@ -0,0 +1,59 @@
+# Copyright (C) 2015 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the GDB testsuite.  It tests the mechanism
+# of exposing types to Python.
+
+load_lib gdb-python.exp
+
+# Note that the purpose of this testcase is to test the behavior
+# of gdb.lookup_type searching for the primitive types internally
+# created by each language since GDB.  So, we must start GDB without
+# loading any symbol in.
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+
+# Skip all tests if Python scripting is not enabled.
+if { [skip_python_tests] } { continue }
+
+proc test_lookup_type { lang type_name } {
+    gdb_test_no_output "set language ${lang}"
+    gdb_test_no_output "python gdb.lookup_type('${type_name}')" \
+        "lookup type ${type_name} using language ${lang}"
+}
+
+test_lookup_type "ada" "character"
+
+test_lookup_type "c" "char"
+
+test_lookup_type "d" "ucent"
+
+test_lookup_type "fortran" "character"
+
+test_lookup_type "go" "int32"
+
+test_lookup_type "java" "byte"
+
+test_lookup_type "modula-2" "CARDINAL"
+
+test_lookup_type "opencl" "ushort"
+
+test_lookup_type "objective-c" "char"
+
+test_lookup_type "opencl" "ushort"
+
+test_lookup_type "pascal" "char"