tests/uefi-test-tools: add build scripts

tests/uefi-test-tools: add build scripts

Introduce the following build scripts under "tests/uefi-test-tools":

* "build.sh" builds a single module (a UEFI application) from
  UefiTestToolsPkg, for a single QEMU emulation target.

  "build.sh" relies on cross-compilers when the emulation target and the
  build host architecture don't match. The cross-compiler prefix is
  computed according to a fixed, Linux-specific pattern. No attempt is
  made to copy or reimplement the GNU Make magic from "qemu/roms/Makefile"
  for cross-compiler prefix determination. The reason is that the build
  host OSes that are officially supported by edk2, and those that are
  supported by QEMU, intersect only in Linux. (Note that the UNIXGCC
  toolchain is being removed from edk2,
  <https://bugzilla.tianocore.org/show_bug.cgi?id=1377>.)

* "Makefile" currently builds the "UefiTestToolsPkg/BiosTablesTest"
  application, for arm, aarch64, i386, and x86_64, with the help of
  "build.sh".

  "Makefile" turns each resultant UEFI executable into a UEFI-bootable,
  qcow2-compressed ISO image. The ISO images are output as
  "tests/data/uefi-boot-images/bios-tables-test.<TARGET>.iso.qcow2".

  Each ISO image should be passed to QEMU as follows:

    -drive id=boot-cd,if=none,readonly,format=qcow2,file=$ISO \
    -device virtio-scsi-pci,id=scsi0 \
    -device scsi-cd,drive=boot-cd,bus=scsi0.0,bootindex=0 \

  "Makefile" assumes that "mkdosfs", "mtools", and "genisoimage" are
  present.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Shannon Zhao <shannon.zhaosl@gmail.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190204160325.4914-5-lersek@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>