Add llvm_unreachable to pacify GCC's dropping off non-void function warning.

+ 80 cols fix.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@192728 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index 8e14d3f..7288402 100644
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -5844,7 +5844,8 @@
   case AR_Available:
   case AR_NotYetIntroduced:
     if (const EnumConstantDecl *EnumConst = dyn_cast<EnumConstantDecl>(D))
-      return getCursorAvailabilityForDecl(cast<Decl>(EnumConst->getDeclContext()));
+      return getCursorAvailabilityForDecl(
+          cast<Decl>(EnumConst->getDeclContext()));
     return CXAvailability_Available;
 
   case AR_Deprecated:
@@ -5853,6 +5854,8 @@
   case AR_Unavailable:
     return CXAvailability_NotAvailable;
   }
+
+  llvm_unreachable("Unknown availability kind!");
 }
 
 enum CXAvailabilityKind clang_getCursorAvailability(CXCursor cursor) {