Support reading GNU symbol versions in ELFObjectFile

include/llvm/Support/ELF.h

Index: include/llvm/Support/ELF.h
===================================================================
--- include/llvm/Support/ELF.h	(revision 152141)
+++ include/llvm/Support/ELF.h	(working copy)
@@ -734,6 +734,9 @@
   SHT_GROUP         = 17, // Section group.
   SHT_SYMTAB_SHNDX  = 18, // Indices for SHN_XINDEX entries.
   SHT_LOOS          = 0x60000000, // Lowest operating system-specific type.
+  SHT_GNU_verdef    = 0x6ffffffd, // GNU version definitions.
+  SHT_GNU_verneed   = 0x6ffffffe, // GNU version references.
+  SHT_GNU_versym    = 0x6fffffff, // GNU symbol versions table.
   SHT_HIOS          = 0x6fffffff, // Highest operating system-specific type.
   SHT_LOPROC        = 0x70000000, // Lowest processor architecture-specific type.
   // Fixme: All this is duplicated in MCSectionELF. Why??
@@ -1102,6 +1105,33 @@
   DF_STATIC_TLS = 0x10  // Reject attempts to load dynamically.
 };
 
+// ElfXX_VerDef structure version (GNU versioning)
+enum {
+  VER_DEF_NONE    = 0,
+  VER_DEF_CURRENT = 1
+};
+
+// VerDef Flags (ElfXX_VerDef::vd_flags)
+enum {
+  VER_FLG_BASE = 0x1,
+  VER_FLG_WEAK = 0x2,
+  VER_FLG_INFO = 0x4
+};
+
+// Special constants for the version table. (SHT_GNU_versym/.gnu.version)
+enum {
+  VER_NDX_LOCAL  = 0,      // Unversioned local symbol
+  VER_NDX_GLOBAL = 1,      // Unversioned global symbol
+  VERSYM_VERSION = 0x7fff, // Version Index mask
+  VERSYM_HIDDEN  = 0x8000  // Hidden bit (non-default version)
+};
+
+// ElfXX_VerNeed structure version (GNU versioning)
+enum {
+  VER_NEED_NONE = 0,
+  VER_NEED_CURRENT = 1
+};
+
 } // end namespace ELF
 
 } // end namespace llvm