Revert r258546.

Seems that the patch was rebased on top of another change which obsoleted the
change but wasnt caught.

Thanks to nbjoerg for pointing this out!

llvm-svn: 258821

lldb/source/Expression/ExpressionSourceCode.cpp

@@ -119,7 +119,6 @@ public:
             default:
                 return false;
         }
-        llvm_unreachable("unhandled state");
     }
 
 private:

lldb/source/Target/Process.cpp

@@ -1501,7 +1501,6 @@ Process::IsAlive ()
         default:
             return false;
     }
-    llvm_unreachable("unhandled state");
 }
 
 // This static callback can be used to watch for local child processes on