Add file to default-configs
Add hexagon to meson.build
Add hexagon to target/meson.build
Add target/hexagon/meson.build
Change scripts/qemu-binfmt-conf.sh

We can build a hexagon-linux-user target and run programs on
the Hexagon scalar core.  With hexagon-linux-clang installed,
"make check-tcg" will pass.

Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <1612763186-18161-35-git-send-email-tsimpson@quicinc.com>
[rth: Use top-level python variable]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>