scripts/kernel-doc: strip QEMU_ from function definitions

scripts/kernel-doc: strip QEMU_ from function definitions

Some packaged versions of Sphinx (fedora33/alpine so far) have issues
with the annotated C code that kernel-doc spits out. Without knowing
about things like QEMU_PLUGIN_EXPORT it chokes trying to understand
the code. Evidently this is a problem for the kernel as well as the
long stream of regex substitutions we add to in this patch can attest.

Fortunately we have a fairly common format for all our compiler
shenanigans as applied to functions so lets just filter them all out.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210323165308.15244-2-alex.bennee@linaro.org>