CMake: support "make programs"

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/programs/util/CMakeLists.txt b/programs/util/CMakeLists.txt
index cb6bc3d..264d941 100644
--- a/programs/util/CMakeLists.txt
+++ b/programs/util/CMakeLists.txt
@@ -6,6 +6,7 @@
     pem2der
     strerror
 )
+add_dependencies(${programs_target} ${executables})
 
 foreach(exe IN LISTS executables)
     add_executable(${exe} ${exe}.c $<TARGET_OBJECTS:mbedtls_test>)