tests: application_development/libxcc: exclude using XCC...

...due to it not supporting standard C++17.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
diff --git a/tests/application_development/libcxx/testcase.yaml b/tests/application_development/libcxx/testcase.yaml
index d689b90..80c5ff0 100644
--- a/tests/application_development/libcxx/testcase.yaml
+++ b/tests/application_development/libcxx/testcase.yaml
@@ -1,10 +1,12 @@
 tests:
   application_development.cpp.libcxx:
     platform_exclude: qemu_x86_coverage
+    toolchain_exclude: xcc
     min_flash: 54
     tags: cpp
   application_development.cpp.libcxx.exceptions:
     platform_exclude: qemu_x86_coverage
+    toolchain_exclude: xcc
     min_flash: 54
     tags: cpp
     extra_configs: