A duplicate insn is one that is appears to be executed twice in a row.
This is currently possible due to -icount and cpu_io_recompile()
causing a re-translation of a block. On it's own this won't trigger
any tests though.

The heuristics that the plugin use can't deal with the x86 rep
instruction which (validly) will look like executing the same
instruction several times. To avoid problems later we tweak the rules
for x86 to run the "inline" version of the plugin. This also has the
advantage of increasing coverage of the plugin code (see bugfix in
previous commit).

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210213130325.14781-15-alex.bennee@linaro.org>