perl.h: Create PERL_UINTMAX_SIZE

This is the sizeof() the widest unsigned available on the platform.
This #define is so that the value can be used in preprocessor
expressions

perl.h

@@ -1201,6 +1201,7 @@ Use L</UV> to declare variables of the maximum usable size on this platform.
     typedef I64TYPE PERL_INTMAX_T;
     typedef U64TYPE PERL_UINTMAX_T;
 #  endif
+#  define PERL_UINTMAX_SIZE U64SIZE
 #  ifndef INTMAX_C
 #    define INTMAX_C(c) INT64_C(c)
 #  endif
@@ -1215,6 +1216,7 @@ Use L</UV> to declare variables of the maximum usable size on this platform.
     typedef I32TYPE PERL_INTMAX_T;
     typedef U32TYPE PERL_UINTMAX_T;
 #  endif
+#  define PERL_UINTMAX_SIZE U32SIZE;
 #  ifndef INTMAX_C
 #    define INTMAX_C(c) INT32_C(c)
 #  endif