Merge remote-tracking branch 'remotes/rth-gitlab/tags/pull-hex-20210218' into staging

Initial commit for the Qualcomm Hexagon processor.

# gpg: Signature made Thu 18 Feb 2021 16:26:52 GMT
# gpg:                using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
# gpg:                issuer "richard.henderson@linaro.org"
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [full]
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A  05C0 64DF 38E8 AF7E 215F

* remotes/rth-gitlab/tags/pull-hex-20210218: (35 commits)
  Hexagon build infrastructure
  Hexagon (tests/tcg/hexagon) TCG tests - floating point
  Hexagon (tests/tcg/hexagon) TCG tests - atomics/load/store/misc
  Hexagon (tests/tcg/hexagon) TCG tests - multiarch
  Hexagon (linux-user/hexagon) Linux user emulation
  Hexagon (target/hexagon) translation
  Hexagon (target/hexagon) TCG for floating point instructions
  Hexagon (target/hexagon) TCG for instructions with multiple definitions
  Hexagon (target/hexagon) TCG generation
  Hexagon (target/hexagon) instruction classes
  Hexagon (target/hexagon) macros
  Hexagon (target/hexagon) opcode data structures
  Hexagon (target/hexagon) generater phase 4 - decode tree
  Hexagon (target/hexagon) generator phase 3 - C preprocessor for decode tree
  Hexagon (target/hexagon) generator phase 2 - generate header files
  Hexagon (target/hexagon) generator phase 1 - C preprocessor for semantics
  Hexagon (target/hexagon/imported) arch import
  Hexagon (target/hexagon/fma_emu.[ch]) utility functions
  Hexagon (target/hexagon/conv_emu.[ch]) utility functions
  Hexagon (target/hexagon/arch.[ch]) utility functions
  ...

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