Stop writing to the source tree.

Due to the directory test/suites being linked, the files generated there
where actually written to the source tree, not just the binary tree.

We no longer need this directory to be linked, that was a remnant of the
time where the .data files were read while running the tests; nowadays
they're processed when generating the test .c file.

Just create the directory, as the generating script quite reasonably
assumes that the output directory passed on the command line exists.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index cddedb4..48716ae 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -13,6 +13,9 @@
     message(FATAL_ERROR "Cannot build test suites without Python 3")
 endif()
 
+# generated .data files will go there
+file(MAKE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/suites)
+
 add_custom_command(
     OUTPUT
         ${CMAKE_CURRENT_BINARY_DIR}/suites/test_suite_psa_crypto_not_supported.generated.data
@@ -215,5 +218,4 @@
     link_to_source(data_files)
     link_to_source(scripts)
     link_to_source(ssl-opt.sh)
-    link_to_source(suites)
 endif()