Move code for MIPS from createInputSection to initializeSections.

[ruiu]

Summary

We already have code for ARM in initializeSections, so this
is more consistent.

[atanasyan]

LGTM

ELF/InputFiles.cpp

case SHT_REL: {
       fatal(getFilename(this) +
             ": relocations pointing to SHF_MERGE are not supported");
     }
     case SHT_ARM_ATTRIBUTES:
       // FIXME: ARM meta-data section. At present attributes are ignored,
       // they can be used to reason about object compatibility.
       Sections[I] = &InputSection<ELFT>::Discarded;
       break;
+    case SHT_MIPS_REGINFO:
+      MipsReginfo.reset(new MipsReginfoInputSection<ELFT>(this, &Sec));
+      Sections[I] = MipsReginfo.get();
+      break;
+    case SHT_MIPS_OPTIONS:
+      MipsOptions.reset(new MipsOptionsInputSection<ELFT>(this, &Sec));
+      Sections[I] = MipsOptions.get();
+      break;
     default:
       Sections[I] = createInputSection(Sec);
     }
   }
 }
 
 template <class ELFT>
 InputSectionBase<ELFT> *
elf::ObjectFile<ELFT>::createInputSection(const Elf_Shdr &Sec) {
   if (Name == ".note.GNU-split-stack") {
     error("objects using splitstacks are not supported");
     return &InputSection<ELFT>::Discarded;
   }
 
   if (Config->StripDebug && Name.startswith(".debug"))
     return &InputSection<ELFT>::Discarded;
 
-  // A MIPS object file has a special sections that contain register
-  // usage info, which need to be handled by the linker specially.
-  if (Config->EMachine == EM_MIPS) {
-    switch (Sec.sh_type) {
-    case SHT_MIPS_REGINFO:
-      MipsReginfo.reset(new MipsReginfoInputSection<ELFT>(this, &Sec));
-      return MipsReginfo.get();
-    case SHT_MIPS_OPTIONS:
-      MipsOptions.reset(new MipsOptionsInputSection<ELFT>(this, &Sec));
-      return MipsOptions.get();
-    }
-  }
-
   // The linker merges EH (exception handling) frames and creates a
   // .eh_frame_hdr section for runtime. So we handle them with a special
   // class. For relocatable outputs, they are just passed through.
   if (Name == ".eh_frame" && !Config->Relocatable)
     return new (EHAlloc.Allocate()) EhInputSection<ELFT>(this, &Sec);
 
   if (shouldMerge(Sec))
     return new (MAlloc.Allocate()) MergeInputSection<ELFT>(this, &Sec);