scripts/clean-includes: Mark 'qemu/qemu-plugin.h' as special header

"qemu/qemu-plugin.h" isn't meant to be include by QEMU codebase,
but by 3rd party plugins that QEMU can use. These plugins can be
built out of QEMU and don't include "qemu/osdep.h".
Mark "qemu/qemu-plugin.h" as a special header that doesn't need
to be cleaned for "qemu/osdep.h".

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200524215654.13256-1-f4bug@amsat.org>
Message-Id: <20200605154929.26910-3-alex.bennee@linaro.org>

scripts/clean-includes

@@ -123,6 +123,7 @@ for f in "$@"; do
       ;;
     *include/qemu/osdep.h | \
     *include/qemu/compiler.h | \
+    *include/qemu/qemu-plugin.h | \
     *include/glib-compat.h | \
     *include/sysemu/os-posix.h | \
     *include/sysemu/os-win32.h | \