Merge remote-tracking branch 'remotes/huth-gitlab/tags/pull-request-2018-12-12' into...

Merge remote-tracking branch 'remotes/huth-gitlab/tags/pull-request-2018-12-12' into staging

- Explicitly check for minimum compiler versions
- Remove obsolete code for old compilers that is now not required anymore
- Fix a duplicated typedef for Clang 3.4

# gpg: Signature made Wed 12 Dec 2018 09:05:50 GMT
# gpg:                using RSA key 2ED9D774FE702DB5
# gpg: Good signature from "Thomas Huth <th.huth@gmx.de>"
# gpg:                 aka "Thomas Huth <thuth@redhat.com>"
# gpg:                 aka "Thomas Huth <huth@tuxfamily.org>"
# gpg:                 aka "Thomas Huth <th.huth@posteo.de>"
# Primary key fingerprint: 27B8 8847 EEE0 2501 18F3  EAB9 2ED9 D774 FE70 2DB5

* remotes/huth-gitlab/tags/pull-request-2018-12-12:
  i2c: Move typedef of bitbang_i2c_interface to i2c.h
  Remove QEMU_ARTIFICIAL macro
  includes: Replace QEMU_GNUC_PREREQ with "__has_builtin || !defined(__clang__)"
  audio/alsaaudio: Remove compiler check around pragma
  tcg/tcg.h: Remove GCC check for tcg_debug_assert() macro
  configure: Remove old -fno-gcse workaround for GCC 4.6.x and 4.7.[012]
  configure: Remove obsolete check for Clang < 3.2
  configure: Add a test for the minimum compiler version

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