[PPC] Support basic form of sc.

tools/ppc-instructions.xml

@@ -1083,7 +1083,8 @@
     <disasm>rlwnm[Rc] [RA], [RS], [RB], [MB], [ME]</disasm>
   </insn>
   <insn mnem="sc"           opcode="44000002" form="SC"       group="b" desc="System Call" sync="true">
-    <disasm>sc</disasm>
+    <in field="LEV" />
+    <disasm>sc [LEV]</disasm>
   </insn>
   <insn mnem="sldx"         opcode="7c000036" form="X"        group="i" desc="Shift Left Doubleword">
     <in field="RS" />

tools/ppc-table-gen

@@ -270,6 +270,8 @@ def generate_token_append(i, token):
     return 'str->AppendFormat(d.%s.%s() < 0 ? "-0x%%X" : "0x%%X", std::abs(d.%s.%s()));' % (i.o_form, token, i.o_form, token)
   elif token == 'ADDR':
     return 'str->AppendFormat("0x%%X", d.%s.%s());' % (i.o_form, token)
+  elif token == 'LEV':
+    return 'if (d.%s.%s()) str->AppendFormat("%%d", d.%s.%s());' % (i.o_form, token, i.o_form, token)
   return 'str->AppendFormat("(UNHANDLED %s)");' % token