tests: c_lib: exclude 64 qemu platform

This one keeps failing sporadically, just exclude for now.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

Author: nashif

tests/lib/c_lib/thrd/testcase.yaml

@@ -30,6 +30,8 @@ tests:
   libraries.libc.c11_threads.picolibc.module:
     filter: CONFIG_ZEPHYR_PICOLIBC_MODULE
     tags: picolibc
+    platform_exclude:
+      - qemu_x86_64/atom
     extra_configs:
       - CONFIG_PICOLIBC=y
       - CONFIG_PICOLIBC_USE_MODULE=y