Replace 'ap' with 'up' suffix in variable names. (NFC)

The `ap` suffix is a remnant of lldb's former use of auto pointers,
before they got deprecated. Although all their uses were replaced by
unique pointers, some variables still carried the suffix.

In r353795 I removed another auto_ptr remnant, namely redundant calls to
::get for unique_pointers. Jim justly noted that this is a good
opportunity to clean up the variable names as well.

I went over all the changes to ensure my find-and-replace didn't have
any undesired side-effects. I hope I didn't miss any, but if you end up
at this commit doing a git blame on a weirdly named variable, please
know that the change was unintentional.

llvm-svn: 353912
diff --git a/lldb/source/Target/OperatingSystem.cpp b/lldb/source/Target/OperatingSystem.cpp
index a950f5e..c78c197 100644
--- a/lldb/source/Target/OperatingSystem.cpp
+++ b/lldb/source/Target/OperatingSystem.cpp
@@ -22,10 +22,10 @@
         PluginManager::GetOperatingSystemCreateCallbackForPluginName(
             const_plugin_name);
     if (create_callback) {
-      std::unique_ptr<OperatingSystem> instance_ap(
+      std::unique_ptr<OperatingSystem> instance_up(
           create_callback(process, true));
-      if (instance_ap)
-        return instance_ap.release();
+      if (instance_up)
+        return instance_up.release();
     }
   } else {
     for (uint32_t idx = 0;
@@ -33,10 +33,10 @@
               PluginManager::GetOperatingSystemCreateCallbackAtIndex(idx)) !=
          nullptr;
          ++idx) {
-      std::unique_ptr<OperatingSystem> instance_ap(
+      std::unique_ptr<OperatingSystem> instance_up(
           create_callback(process, false));
-      if (instance_ap)
-        return instance_ap.release();
+      if (instance_up)
+        return instance_up.release();
     }
   }
   return nullptr;