Add a metatest program

This program can be used to validate that things that should be detected as
test failures are indeed caught, either by setting the test result to
MBEDTLS_TEST_RESULT_FAILED or by aborting the program.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/programs/test/CMakeLists.txt b/programs/test/CMakeLists.txt
index a75f8d9..8469d06 100644
--- a/programs/test/CMakeLists.txt
+++ b/programs/test/CMakeLists.txt
@@ -3,6 +3,7 @@
 )
 
 set(executables_libs
+    metatest
     query_included_headers
     selftest
     udp_proxy