o3tl: 32-bit clang 4.0.1 fails with undefined reference to `__mulodi4'

... so prevent it from using __builtin_mul_overflow().

Change-Id: Id716f88abb0385701b6df42353b663479abfd496

include/o3tl/safeint.hxx

@@ -82,7 +82,8 @@ template<typename T> inline bool checked_sub(T a, T b, T& result)
     return !msl::utilities::SafeSubtract(a, b, result);
 }
 
-#elif (defined __GNUC__ && __GNUC__ >= 5) || (__has_builtin(__builtin_mul_overflow) && !(defined ANDROID && defined __clang__))
+#elif (defined __GNUC__ && __GNUC__ >= 5) || (__has_builtin(__builtin_mul_overflow) && !(defined ANDROID && defined __clang__) && !(defined(__clang__) && defined(__i386__) && __clang_major__ == 4))
+// 32-bit clang 4.0.1 fails with undefined reference to `__mulodi4'
 
 template<typename T> inline bool checked_multiply(T a, T b, T& result)
 {