[blktest] Add arg flag help and use standrd arg parsing

blktest fails without blkdev_path being set properly, so make it clear
to the user and add handling for -h and incorrect execution.

Change-Id: Ief5e67441b62fab3f34c0cb8dcb2120148b6cd9c

[udev][sata] use block fifo

Currently, if the VMO passed in is non contiguous the operation will fail. Scatter
gather coming in the next CL.

Change-Id: I9e1ccfd4914fa3795fa48418b1fb86b86a50f94e

[userspace] Use PRI?64 macros instead of %ll?

Bug: MG-164

This is the official way to print *int64_t types.

Change-Id: Ib4c7c814a62678650b1691bc1925635235ade217

[blktest] Use ioctl wrappers

Change-Id: Ic307ed541acbc55acfd1dc38cee46d55d2ca5036

[blktest] free the test buffer

Change-Id: I647142643d288d698c6c9bab2a9023aad6780267

[magenta] migrate from libddk to magenta/device headers

Change-Id: I91a8df001043635fa595d6fed1a6d6f092fc6b3e

[gpt] fix off by one error in iotxn_queue

Change-Id: Ia0dcdb5cc1745e34eaefd7bf182d69fd9c2be7b6

[magenta][ddk] normalize ioctl defines

- ioctls are now unique
- ioctls now encode a kind, family, and number
- ioctls that return a handle are of IOCTL_KIND_GET_HANDLE
- remoteio plumbing updated to reflect this
- drivers and ioctl users updated

Change-Id: Ic202cec6336a4915b09e3cbfff5dc6389f397288

[system] align license and license banners with Fuchsia

This adjusts the Magenta userspace code to match the prevailing
license in Fuchsia (three-clause BSD), using the same banner
and license text.

Change-Id: I6b6d79435c5dbaa32027888874849e4f47aaa7be

[sata] support transfers > 4mb

Change-Id: I9ff9ceef5cc629d935c66ebbd5bc866f31f40981

[udev] use iotxn in rpc read and write, implement sata write

MX_RIO_READ and MX_RIO_WRITE will issue an iotxn to the driver and
synchronously wait for its completion. Add blktest utility.

Also enable ahci support in qemu. Invoking qemu with -d will enable a
block device on ahci instead of virtio. (make a disk image named blk.bin)

Change-Id: I69c8d6e6d789ffd3e28422b5914775b91864965f