Avoid the direct use of 'defined' in macro expansion

[juergenhoetzel]

If a defined operator appears as the result of a macro expansion, the
C standard specifies the behavior as undefined.

Fixes "-Wexpansion-to-defined" warnings produced by clang >=3.9:

poly1305-donna.c:18:6: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined]
#if (HAS_SIZEOF_INT128_64BIT || HAS_MSVC_64BIT || HAS_GCC_4_4_64BIT)
     ^
poly1305-donna.c:14:34: note: expanded from macro 'HAS_SIZEOF_INT128_64BIT'
#define HAS_SIZEOF_INT128_64BIT (defined(__SIZEOF_INT128__) && defined(__LP64__))
                                 ^
poly1305-donna.c:18:6: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined]
poly1305-donna.c:14:64: note: expanded from macro 'HAS_SIZEOF_INT128_64BIT'
#define HAS_SIZEOF_INT128_64BIT (defined(__SIZEOF_INT128__) && defined(__LP64__))
                                                               ^
poly1305-donna.c:18:33: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined]
#if (HAS_SIZEOF_INT128_64BIT || HAS_MSVC_64BIT || HAS_GCC_4_4_64BIT)
                                ^
poly1305-donna.c:15:25: note: expanded from macro 'HAS_MSVC_64BIT'
#define HAS_MSVC_64BIT (defined(_MSC_VER) && defined(_M_X64))
                        ^
poly1305-donna.c:18:33: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined]
poly1305-donna.c:15:46: note: expanded from macro 'HAS_MSVC_64BIT'
#define HAS_MSVC_64BIT (defined(_MSC_VER) && defined(_M_X64))
                                             ^
poly1305-donna.c:18:51: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined]
#if (HAS_SIZEOF_INT128_64BIT || HAS_MSVC_64BIT || HAS_GCC_4_4_64BIT)
                                                  ^
poly1305-donna.c:16:28: note: expanded from macro 'HAS_GCC_4_4_64BIT'
#define HAS_GCC_4_4_64BIT (defined(__GNUC__) && defined(__LP64__) && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 4))))
                           ^
poly1305-donna.c:18:51: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined]
poly1305-donna.c:16:49: note: expanded from macro 'HAS_GCC_4_4_64BIT'
#define HAS_GCC_4_4_64BIT (defined(__GNUC__) && defined(__LP64__) && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 4))))

Issue appeared in john the ripper:

• Restic issues openwall/john#4537
• Avoid the direct use of 'defined' in macro expansion

[solardiz]

Looks like #5 is a different attempt at fixing the same.