cpp: Fix C++ exception handling newlib dependency

This commit makes C++ exception handling feature depend on the full
version of newlib (i.e. `CONFIG_NEWLIB_LIBC_NANO=n`).

The `nano.specs`, which selects the nano variant of newlib, libstdc++,
and libsupc++, does not support C++ exception handling because its
lib*c++ is compiled with `-fno-exceptions`.

For more details, refer to the issue #35972.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>

subsys/cpp/Kconfig

@@ -54,6 +54,7 @@ if LIB_CPLUSPLUS
 
 config EXCEPTIONS
 	bool "Enable C++ exceptions support"
+	depends on !NEWLIB_LIBC_NANO
 	help
 	  This option enables support of C++ exceptions.