tests: cpp: cxx: Test with various types of libc

This commit changes the C++ subsystem test, which previously was only
being run with the minimal libc, to be run with all the mainstream C
libraries (minimal libc, newlib, newlib-nano, picolibc).

Signed-off-by: Stephanos Ioannidis <[email protected]>
(cherry picked from commit 03f0693)

Author: stephanosio

tests/subsys/cpp/cxx/testcase.yaml

@@ -1,5 +1,21 @@
-tests:
-  cpp.main:
+common:
+    tags: cpp
     integration_platforms:
       - mps2_an385
-    tags: cpp
+
+tests:
+  cpp.main.minimal:
+    extra_configs:
+      - CONFIG_MINIMAL_LIBC=y
+  cpp.main.newlib:
+    filter: TOOLCHAIN_HAS_NEWLIB == 1
+    min_ram: 32
+    extra_configs:
+      - CONFIG_NEWLIB_LIBC=y
+      - CONFIG_NEWLIB_LIBC_NANO=n
+  cpp.main.newlib_nano:
+    filter: TOOLCHAIN_HAS_NEWLIB == 1 and CONFIG_HAS_NEWLIB_LIBC_NANO
+    min_ram: 24
+    extra_configs:
+      - CONFIG_NEWLIB_LIBC=y
+      - CONFIG_NEWLIB_LIBC_NANO=y