build: Don't enable tests or examples in subprojects

This just adds dependency lookup time and extra build targets that are
unused by the main project. They can still be overridden if required.

Change-Id: Ib1d14aa035680c43e6659ab3feae3a3ca3d515ba
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/meson.build b/meson.build
index 6cacf8c..7edf7de 100644
--- a/meson.build
+++ b/meson.build
@@ -3,6 +3,8 @@
       'buildtype=debugoptimized',
       'cpp_std=c++17',
       'werror=true',
+      'tests=' + (meson.is_subproject() ? 'disabled' : 'auto'),
+      'examples=' + (meson.is_subproject() ? 'disabled' : 'auto'),
     ],
     version: '1.0.0',
 )