Merge remote-tracking branch 'remotes/lersek/tags/edk2-pull-2019-04-22' into staging

Advance the roms/edk2 submodule to the "edk2-stable201903" release, and
build and capture platform firmware binaries from that release. The
binaries are meant to be used by both end-users and by the "BIOS tables"
unit tests in qtest ("make check").

# gpg: Signature made Mon 22 Apr 2019 19:20:08 BST
# gpg:                using RSA key D39DA71E0D496CFA
# gpg: Good signature from "Laszlo Ersek <lersek@redhat.com>" [marginal]
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: F5D9 660F 1BA5 F310 A95A  C5E0 466A EAE0 6125 3988
#      Subkey fingerprint: B3A5 5D3F 88A8 90ED 2E63  3E8D D39D A71E 0D49 6CFA

* remotes/lersek/tags/edk2-pull-2019-04-22:
  MAINTAINERS: add the "EDK2 Firmware" subsystem
  Makefile: install the edk2 firmware images and their descriptors
  tests: add missing dependency to build QTEST_QEMU_BINARY, round 2
  pc-bios: document the edk2 firmware images; add firmware descriptors
  pc-bios: add edk2 firmware binaries and variable store templates
  roms: build edk2 firmware binaries and variable store templates
  roms/Makefile: replace the $(EDK2_EFIROM) target with "edk2-basetools"
  roms/edk2-funcs.sh: add the qemu_edk2_get_thread_count() function
  roms/edk2: advance to tag edk2-stable201903
  tests/uefi-test-tools/build.sh: work around TianoCore#1607
  roms/edk2-funcs.sh: require gcc-4.8+ for building i386 and x86_64
  roms: lift "edk2-funcs.sh" from "tests/uefi-test-tools/build.sh"

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --cc MAINTAINERS
Simple merge