Merge remote-tracking branch 'remotes/philmd-gitlab/tags/avr-20200721' into staging

Merge remote-tracking branch 'remotes/philmd-gitlab/tags/avr-20200721' into staging

AVR patches

Fixes a memory leak reported by Coverity (CID 1430449).

CI jobs result:
. https://gitlab.com/philmd/qemu/-/pipelines/168722631

# gpg: Signature made Tue 21 Jul 2020 19:00:03 BST
# gpg:                using RSA key FAABE75E12917221DCFD6BB2E3E32C2CDEADC0DE
# gpg: Good signature from "Philippe Mathieu-Daudé (F4BUG) <[email protected]>" [full]
# Primary key fingerprint: FAAB E75E 1291 7221 DCFD  6BB2 E3E3 2C2C DEAD C0DE

* remotes/philmd-gitlab/tags/avr-20200721:
  hw/avr/boot: Fix memory leak in avr_load_firmware()
  qemu-common: Document qemu_find_file()
  qemu/osdep: Reword qemu_get_exec_dir() documentation
  qemu/osdep: Document os_find_datadir() return value

Signed-off-by: Peter Maydell <[email protected]>