str/cat: Rename from util/string

This still maintains backwards compatability.

Change-Id: Id984a9c2067aaa6986f892c1870834d77b8aec80
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/test/meson.build b/test/meson.build
index 16e1e77..2f1d7f9 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -6,8 +6,8 @@
   'pinned': [stdplus_dep, gtest_main_dep],
   'raw': [stdplus_dep, gmock_dep, gtest_main_dep],
   'signal': [stdplus_dep, gtest_main_dep],
+  'str/cat': [stdplus_dep, gtest_main_dep],
   'util/cexec': [stdplus_dep, gtest_main_dep],
-  'util/string': [stdplus_dep, gtest_main_dep],
   'zstring': [stdplus_dep, gtest_main_dep],
   'zstring_view': [stdplus_dep, gtest_main_dep],
 }