tests: libcxx: Filter libstdc++ tests by TOOLCHAIN_HAS_GLIBCXX

Run libstdc++ tests only using the toolchains that have libstdc++ (i.e.
GCC-based toolchain).

Signed-off-by: Stephanos Ioannidis <[email protected]>

Author: stephanosio

tests/lib/cpp/libcxx/testcase.yaml

@@ -4,7 +4,7 @@ common:
     - rx
 tests:
   cpp.libcxx.glibcxx.newlib:
-    filter: TOOLCHAIN_HAS_NEWLIB == 1
+    filter: TOOLCHAIN_HAS_GLIBCXX == 1 and TOOLCHAIN_HAS_NEWLIB == 1
     toolchain_exclude: xcc
     min_flash: 54
     min_ram: 24
@@ -16,7 +16,7 @@ tests:
     integration_platforms:
       - mps2/an385
   cpp.libcxx.glibcxx.newlib_nano:
-    filter: TOOLCHAIN_HAS_NEWLIB == 1 and CONFIG_HAS_NEWLIB_LIBC_NANO
+    filter: TOOLCHAIN_HAS_GLIBCXX == 1 and TOOLCHAIN_HAS_NEWLIB == 1 and CONFIG_HAS_NEWLIB_LIBC_NANO
     toolchain_exclude: xcc
     min_flash: 54
     tags: cpp
@@ -28,7 +28,7 @@ tests:
     integration_platforms:
       - mps2/an385
   cpp.libcxx.glibcxx.picolibc:
-    filter: TOOLCHAIN_HAS_PICOLIBC == 1
+    filter: TOOLCHAIN_HAS_GLIBCXX == 1 and TOOLCHAIN_HAS_PICOLIBC == 1
     toolchain_exclude: xcc
     tags: cpp
     timeout: 60