Remove doesSectionRequireSymbols.

In an assembly expression like

bar:
.long L0 + 1

the intended semantics is that bar will contain a pointer one byte past L0.

In sections that are merged by content (strings, 4 byte constants, etc), a
single position in the section doesn't give the linker enough information.
For example, it would not be able to tell a relocation must point to the
end of a string, since that would look just like the start of the next.

The solution used in ELF to use relocation with symbols if there is a non-zero
addend.

In MachO before this patch we would just keep all symbols in some sections.

This would miss some cases (only cstrings on x86_64 were implemented) and was
inefficient since most relocations have an addend of 0 and can be represented
without the symbol.

This patch implements the non-zero addend logic for MachO too.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224985 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCObjectWriter.h

@@ -76,12 +76,10 @@ public:
   /// post layout binding. The implementation is responsible for storing
   /// information about the relocation so that it can be emitted during
   /// WriteObject().
-  virtual void RecordRelocation(const MCAssembler &Asm,
-                                const MCAsmLayout &Layout,
+  virtual void RecordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
                                 const MCFragment *Fragment,
                                 const MCFixup &Fixup, MCValue Target,
-                                bool &IsPCRel,
-                                uint64_t &FixedValue) = 0;
+                                bool &IsPCRel, uint64_t &FixedValue) = 0;
 
   /// \brief Check whether the difference (A - B) between two symbol
   /// references is fully resolved.