Add r228980 back.

Add support for having multiple sections with the same name and comdat.

Using this in combination with -ffunction-sections allows LLVM to output a .o
file with mulitple sections named .text. This saves space by avoiding long
unique names of the form .text.<C++ mangled name>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229541 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCContext.h

@@ -277,6 +277,10 @@ namespace llvm {
                                       unsigned Flags, unsigned EntrySize,
                                       StringRef Group);
 
+    const MCSectionELF *getELFSection(StringRef Section, unsigned Type,
+                                      unsigned Flags, unsigned EntrySize,
+                                      StringRef Group, bool Unique);
+
     void renameELFSection(const MCSectionELF *Section, StringRef Name);
 
     const MCSectionELF *CreateELFGroupSection();