OS-7095 Want risc-v disassembler

*** 22,31 ****
--- 22,32 ----
  /*
   * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   * Copyright 2012 Joshua M. Clulow <josh@sysmgr.org>
   * Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
+  * Copyright 2018, Joyent, Inc.
   */
  
  #include <libdisasm.h>
  #include <stdlib.h>
  #ifdef DIS_STANDALONE
*** 53,62 ****
--- 54,66 ----
  extern dis_arch_t dis_arch_sparc;
  #endif
  #if !defined(DIS_STANDALONE) || defined(__s390) || defined(__s390x)
  extern dis_arch_t dis_arch_s390;
  #endif
+ #if !defined(DIS_STANDALONE) || defined(__riscv)
+ extern dis_arch_t dis_arch_riscv;
+ #endif
  
  static dis_arch_t *dis_archs[] = {
  #if !defined(DIS_STANDALONE) || defined(__i386) || defined(__amd64)
          &dis_arch_i386,
  #endif
*** 64,73 ****
--- 68,80 ----
          &dis_arch_sparc,
  #endif
  #if !defined(DIS_STANDALONE) || defined(__s390) || defined(__s390x)
          &dis_arch_s390,
  #endif
+ #if !defined(DIS_STANDALONE) || defined(__riscv)
+         &dis_arch_riscv,
+ #endif
          NULL
  };
  
  /*
   * For the standalone library, we need to link against mdb's malloc/free.