Fixing missing max_align_t error

lib/algorithms/approx/Remez.cc

@@ -11,7 +11,8 @@
   Note this class requires the gnu multiprecision (GNU MP) library.
 
 */
-
+// fixing ::max_align_t error for some versions of g++/clang++
+#include<stddef.h>
 #include<math.h>
 #include<stdio.h>
 #include<stdlib.h>