Compute the ELF SectionKind from the flags.

Any code creating an MCSectionELF knows ELF and already provides the flags.

SectionKind is an abstraction used by common code that uses a plain
MCSection.

Use the flags to compute the SectionKind. This removes a lot of
guessing and boilerplate from the MCSectionELF construction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227476 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCSectionELF.h

@@ -92,10 +92,6 @@ public:
   static bool classof(const MCSection *S) {
     return S->getVariant() == SV_ELF;
   }
-
-  // Return the entry size for sections with fixed-width data.
-  static unsigned DetermineEntrySize(SectionKind Kind);
-
 };
 
 } // end namespace llvm