Silence snprintf truncation warnings in printf_test examples
Building share/examples/tests with clang 18 results in a few warnings
like:
share/examples/tests/tests/plain/printf_test.c:67:6: error: 'snprintf' will always be truncated; specified size is 10, but format string expands to at least 17 [-Werror,-Wformat-truncation]
67 | if (snprintf(buffer, sizeof(buffer), "0123456789abcdef") != 16)
| ^Since these tests are meant as an example of testing snprintf overflow,
suppress the warnings.
MFC after: 3 days