Unbreak gcc.

[davide]

Summary

../tools/lld/ELF/InputSection.h: In constructor ‘lld::elf::SectionPiece::SectionPiece(size_t, llvm::ArrayRef<unsigned char>)’:
../tools/lld/ELF/InputSection.h:90:50: warning: cast from type ‘const unsigned char*’ to type ‘uint8_t* {aka unsigned char*}’ casts away qualifiers [-Wcast-qual]
       : InputOff(Off), Data((uint8_t *)Data.data()), Size(Data.size()),
                                                  ^

[ruiu]

LGTM

ELF/InputSection.h

public:
   std::vector<Relocation> Relocations;
 };
 
 template <class ELFT> InputSectionBase<ELFT> InputSectionBase<ELFT>::Discarded;
 
 // SectionPiece represents a piece of splittable section contents.
 struct SectionPiece {
   SectionPiece(size_t Off, ArrayRef<uint8_t> Data)
-      : InputOff(Off), Data((uint8_t *)Data.data()), Size(Data.size()),
+      : InputOff(Off), Data((const uint8_t *)Data.data()), Size(Data.size()),
         Live(!Config->GcSections) {}
 
   ArrayRef<uint8_t> data() { return {Data, Size}; }
   size_t size() const { return Size; }
 
   size_t InputOff;
   size_t OutputOff = -1;
 
 private:
   // We use bitfields because SplitInputSection is accessed by
   // std::upper_bound very often.
   // We want to save bits to make it cache friendly.
-  uint8_t *Data;
+  const uint8_t *Data;
   uint32_t Size : 31;
 
 public:
   uint32_t Live : 1;
 };
 
 // Usually sections are copied to the output as atomic chunks of data,
 // but some special types of sections are split into small pieces of data