util/cexec: Implement exception helpers

See src/stdplus/util/cexec.hpp callCheckErrno for the motivation behind
this change.

Change-Id: I0225b87398b632624f2ef8ccd6c00b5dd6b7e056
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/test/meson.build b/test/meson.build
index cc3d12d..f11864e 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -5,6 +5,7 @@
   'signal',
   'handle/copyable',
   'handle/managed',
+  'util/cexec',
 ]
 
 foreach t : tests