tests: Move the trietest unit test into base.

This puts it alongside trie.hh, the header file it tests.

Change-Id: Id8ca0c1d68bdc01807c5ba4b51c0142b1221385d
Reviewed-on: https://gem5-review.googlesource.com/6281
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>

src/base/SConscript

@@ -64,6 +64,7 @@ Source('statistics.cc')
 Source('str.cc')
 Source('time.cc')
 Source('trace.cc')
+GTest('trietest', 'trietest.cc')
 Source('types.cc')
 
 Source('loader/aout_object.cc')