Rework MSVC warning suppression

Previously, MSVC warning C4996 was suppressed unconditionally in the
entire code base which made it difficult identifying and fixing specific
problems, particularly those in the public interface.

Prefer now to disable warnings at the specific location they occur. This
approach, however, reveals an inconsistency in how Ceres handles POSIX
functions which are declared deprecated by MSVC. Specifically, Bessel
functions use the underscore form whereas the read function does not. To
simplify the logic, we revert to POSIX compatible functions.

C++23 also deprecates std::numeric_limits<T>::has_denorm which MSVC
warns about. Here, we disable the deprecation warning locally to avoid
the warning leaking into the user code.

Fixes #1013

Change-Id: Ida8457cc8dd8770b4384a7c49d16f213b02cdec4

include/ceres/internal/port.h

diff --git a/include/ceres/internal/port.h b/include/ceres/internal/port.h
index e61ef52..b8cb0ff 100644
--- a/include/ceres/internal/port.h
+++ b/include/ceres/internal/port.h
@@ -77,4 +77,15 @@
 //
 #define CERES_PREVENT_MACRO_SUBSTITUTION  // Yes, it's empty
 
+// CERES_DISABLE_DEPRECATED_WARNING and CERES_RESTORE_DEPRECATED_WARNING allow
+// to temporarily disable deprecation warnings
+#if defined(_MSC_VER)
+#define CERES_DISABLE_DEPRECATED_WARNING \
+  _Pragma("warning(push)") _Pragma("warning(disable : 4996)")
+#define CERES_RESTORE_DEPRECATED_WARNING _Pragma("warning(pop)")
+#else  // defined(_MSC_VER)
+#define CERES_DISABLE_DEPRECATED_WARNING
+#define CERES_RESTORE_DEPRECATED_WARNING
+#endif  // defined(_MSC_VER)
+
 #endif  // CERES_PUBLIC_INTERNAL_PORT_H_