[Courgette] Refactor: Add and use Instruction*Receptor classes; call ParseFile() in 2 passes.

courgette/disassembler_win32_x86.cc

Index: courgette/disassembler_win32_x86.cc
diff --git a/courgette/disassembler_win32_x86.cc b/courgette/disassembler_win32_x86.cc
index 10f66aba3034da5cde7d53f18a121b7833849b42..e34574a180157ba2a0ac293f9d6f0baf2001c3f6 100644
--- a/courgette/disassembler_win32_x86.cc
+++ b/courgette/disassembler_win32_x86.cc
@@ -31,8 +31,8 @@ RVA DisassemblerWin32X86::Address32ToRVA(uint32_t address) const {
 }
 
 CheckBool DisassemblerWin32X86::EmitAbs(Label* label,
-                                        AssemblyProgram* program) {
-  return program->EmitAbs32(label);
+                                        InstructionReceptor* receptor) const {
+  return receptor->EmitAbs32(label);
 }
 
 void DisassemblerWin32X86::ParseRel32RelocsFromSection(const Section* section) {