tests/libcxx: Exclude native_sim from picolibc/newlib + libstdc++ tests

While we use the Zephyr SDK, which declares that it supports picolibc and
libstdc++, when building native_sim, we'll be using the native C compiler
which means using the picolibc module and not supporting libstdc++.

Signed-off-by: Keith Packard <keithp@keithp.com>

Author: keith-packard

tests/lib/cpp/libcxx/testcase.yaml

@@ -7,6 +7,7 @@ tests:
   cpp.libcxx.glibcxx.newlib:
     filter: TOOLCHAIN_HAS_GLIBCXX == 1 and TOOLCHAIN_HAS_NEWLIB == 1
     toolchain_exclude: xcc
+    platform_exclude: native_sim
     min_flash: 54
     min_ram: 24
     tags: cpp
@@ -19,6 +20,7 @@ tests:
   cpp.libcxx.glibcxx.newlib_nano:
     filter: TOOLCHAIN_HAS_GLIBCXX == 1 and TOOLCHAIN_HAS_NEWLIB == 1 and CONFIG_HAS_NEWLIB_LIBC_NANO
     toolchain_exclude: xcc
+    platform_exclude: native_sim
     min_flash: 54
     tags: cpp
     timeout: 60
@@ -31,6 +33,7 @@ tests:
   cpp.libcxx.glibcxx.picolibc:
     filter: TOOLCHAIN_HAS_GLIBCXX == 1 and TOOLCHAIN_HAS_PICOLIBC == 1
     toolchain_exclude: xcc
+    platform_exclude: native_sim
     tags: cpp
     timeout: 60
     extra_configs:
@@ -43,6 +46,7 @@ tests:
   cpp.libcxx.libcxx.picolibc:
     filter: TOOLCHAIN_HAS_LIBCXX == 1 and TOOLCHAIN_HAS_PICOLIBC == 1
     toolchain_exclude: xcc
+    platform_exclude: native_sim
     tags: cpp
     timeout: 60
     extra_configs: