Lots of RISC-V improvements.

This represents months of continuing RISC-V work, with too many changes
to list individually. Some improvements:
* Fixed memory leaks.
* Better handling of dbus timeouts.
* Add `riscv expose_custom` command.
* Somewhat deal with cache coherency.
* Deal with more timeouts during block memory accesses.
* Basic debug compliance test.
* Tell gdb which watchpoint hit.
* SMP support for use with -rtos hwthread
* Add `riscv set_ir`

Change-Id: Ica507ee2a57eaf51b578ab1d9b7de71512fdf47f
Signed-off-by: Tim Newsome <tim@sifive.com>
Reviewed-on: http://openocd.zylin.com/4922
Tested-by: jenkins
Reviewed-by: Philipp Guehring <pg@futureware.at>
Reviewed-by: Liviu Ionescu <ilg@livius.net>
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>

src/target/riscv/program.h

@@ -52,8 +52,8 @@ int riscv_program_insert(struct riscv_program *p, riscv_insn_t i);
  * memory. */
 int riscv_program_save_to_dscratch(struct riscv_program *p, enum gdb_regno to_save);
 
-/* Helpers to assembly various instructions.  Return 0 on success.  These might
- * assembly into a multi-instruction sequence that overwrites some other
+/* Helpers to assemble various instructions.  Return 0 on success.  These might
+ * assemble into a multi-instruction sequence that overwrites some other
  * register, but those will be properly saved and restored. */
 int riscv_program_lwr(struct riscv_program *p, enum gdb_regno d, enum gdb_regno a, int o);
 int riscv_program_lhr(struct riscv_program *p, enum gdb_regno d, enum gdb_regno a, int o);