tools/fuzz: Add a cpu-policy fuzzing harness

There is now enough complexity that a fuzzing harness is a good idea, and
enough supporting logic to implement one which AFL seems happy with.

Take the existing recalculate_synth() helper and export it as
x86_cpuid_policy_recalc_synth(), as it is needed by the fuzzing harness.

While editing the MAINTAINERS file, insert a related entry which was
accidentally missed from c/s 919ddc3c0 "tools/cpu-policy: Add unit tests", and
sort the lines.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

MAINTAINERS

@@ -449,8 +449,10 @@ F:	xen/lib/x86
 F:	tools/firmware/hvmloader/
 F:	tools/firmware/rombios/
 F:	tools/firmware/vgabios/
-F:	tools/tests/x86_emulator/
+F:	tools/fuzz/cpu-policy/
 F:	tools/fuzz/x86_instruction_emulator/
+F:	tools/tests/cpu-policy/
+F:	tools/tests/x86_emulator/
 
 X86 I/O EMULATION
 M:	Paul Durrant <paul.durrant@citrix.com>