add AvailableExternally linkage to C bindings.

llvm-svn: 68942
diff --git a/llvm/include/llvm-c/Core.h b/llvm/include/llvm-c/Core.h
index 91b3bdf..3d5be53 100644
--- a/llvm/include/llvm-c/Core.h
+++ b/llvm/include/llvm-c/Core.h
@@ -115,6 +115,7 @@
 
 typedef enum {
   LLVMExternalLinkage,    /**< Externally visible function */
+  LLVMAvailableExternallyLinkage,
   LLVMLinkOnceAnyLinkage, /**< Keep one copy of function when linking (inline)*/
   LLVMLinkOnceODRLinkage, /**< Same, but only replaced by something
                             equivalent. */