in sys/procfs.h, avoid using __WORDSIZE macro

this was problematic because several archs don't define __WORDSIZE. we
could add it, but I would rather phase this macro out in the long
term. in our version of the headers, UINTPTR_MAX is available here, so
just use it instead.

include/sys/procfs.h

@@ -40,7 +40,7 @@ struct elf_prpsinfo
 	char pr_zomb;
 	char pr_nice;
 	unsigned long int pr_flag;
-#if __WORDSIZE == 32
+#if UINTPTR_MAX == 0xffffffff
 	unsigned short int pr_uid;
 	unsigned short int pr_gid;
 #else