Add a new "available_externally" linkage type.  This is intended
to support C99 inline, GNU extern inline, etc.  Related bugzilla's
include PR3517, PR3100, & PR2933.  Nothing uses this yet, but it
appears to work.

llvm-svn: 68940
diff --git a/llvm/lib/Linker/LinkModules.cpp b/llvm/lib/Linker/LinkModules.cpp
index 0ca4e10f..4a15d88 100644
--- a/llvm/lib/Linker/LinkModules.cpp
+++ b/llvm/lib/Linker/LinkModules.cpp
@@ -480,9 +480,10 @@
   } else if (Src->isWeakForLinker()) {
     // At this point we know that Dest has LinkOnce, External*, Weak, Common,
     // or DLL* linkage.
-    if ((Dest->hasLinkOnceLinkage() &&
-          (Src->hasWeakLinkage() || Src->hasCommonLinkage())) ||
-        Dest->hasExternalWeakLinkage()) {
+    if (Dest->hasExternalWeakLinkage() ||
+        Dest->hasAvailableExternallyLinkage() ||
+        (Dest->hasLinkOnceLinkage() &&
+         (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) {
       LinkFromSrc = true;
       LT = Src->getLinkage();
     } else {