str/maps: Add commonly used cheaper string map

These maps allow for the use of string_views to find elements so we
don't need to construct std::strings for lookups.

Change-Id: I92040b920bf8e231346bebfe9afa59f1a37b8af5
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/include/meson.build b/include/meson.build
index 1a1eb6f..8b8b1dd 100644
--- a/include/meson.build
+++ b/include/meson.build
@@ -15,6 +15,7 @@
   'stdplus/signal.hpp',
   'stdplus/str/cat.hpp',
   'stdplus/str/cexpr.hpp',
+  'stdplus/str/maps.hpp',
   'stdplus/util/cexec.hpp',
   'stdplus/util/string.hpp',
   'stdplus/zstring.hpp',