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

courgette/disassembler_elf_32_x86.h

Index: courgette/disassembler_elf_32_x86.h
diff --git a/courgette/disassembler_elf_32_x86.h b/courgette/disassembler_elf_32_x86.h
index bea7d78033c8430ec06bd0ba5373e2d2992aaa7a..ff4fad8707a9ea05a0f73cca920d47967c10cacb 100644
--- a/courgette/disassembler_elf_32_x86.h
+++ b/courgette/disassembler_elf_32_x86.h
@@ -17,6 +17,7 @@
 namespace courgette {
 
 class AssemblyProgram;
+class InstructionReceptor;
 
 class DisassemblerElf32X86 : public DisassemblerElf32 {
  public:
@@ -32,8 +33,8 @@ class DisassemblerElf32X86 : public DisassemblerElf32 {
 
     // TypedRVA interfaces.
     CheckBool ComputeRelativeTarget(const uint8_t* op_pointer) override;
-    CheckBool EmitInstruction(AssemblyProgram* program,
-                              Label* label) override;
+    CheckBool EmitInstruction(Label* label,
+                              InstructionReceptor* receptor) override;
     uint16_t op_size() const override;
   };
 
@@ -50,8 +51,8 @@ class DisassemblerElf32X86 : public DisassemblerElf32 {
   CheckBool RelToRVA(Elf32_Rel rel,
                      RVA* result) const override WARN_UNUSED_RESULT;
   CheckBool ParseRelocationSection(const Elf32_Shdr* section_header,
-                                   AssemblyProgram* program)
-      override WARN_UNUSED_RESULT;
+                                   InstructionReceptor* receptor) const override
+      WARN_UNUSED_RESULT;
   CheckBool ParseRel32RelocsFromSection(const Elf32_Shdr* section)
       override WARN_UNUSED_RESULT;