Mark string_ref's strlen as a Flawfinder false positive

string_ref(const char*) requires a null-terminated string, like
std::string_view's constructor.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

include/nlohmann/detail/view/string_ref.hpp

@@ -40,6 +40,8 @@ class string_ref
     using const_iterator = const char*;
 
     string_ref() noexcept = default;
+    // s must be null-terminated, as for std::string_view(const char*)
+    // flawfinder: ignore
     string_ref(const char* s) : m_data(s), m_size(std::strlen(s)) {} // NOLINT(google-explicit-constructor,hicpp-explicit-conversions)
     string_ref(const char* s, std::size_t n) noexcept : m_data(s), m_size(n) {}
     template<typename Traits, typename Alloc>