Bug 1663217 - Remove MOZ_MUST_USE comment from NSIS BitsUtils.cpp. r=agashlin

The MOZ_MUST_USE macro is defined as clang's and gcc's nonstandard __attribute__((warn_unused_result)). Now that we compile as C++17 by default (bug 1560664), we can replace MOZ_MUST_USE with C++17's standard [[nodiscard]] attribute.

BitsUtils.cpp only references MOZ_MUST_USE in a comment about forking a copy of mozilla::ScopeExit to remove some dependencies on other Mozilla header files (including MOZ_MUST_USE from mfbt/Attributes.h). [[nodiscard]] doesn't require a header file, so we can just remove this comment about MOZ_MUST_USE.

Differential Revision: https://phabricator.services.mozilla.com/D89296

other-licenses/nsis/Contrib/BitsUtils/BitsUtils.cpp

@@ -16,7 +16,7 @@ static HINSTANCE gHInst;
 
 // ***** Section: ScopeExit
 // Derived from mfbt mozilla::ScopeExit, I have removed the use of
-// GuardObjectNotifier and annotations MOZ_STACK_CLASS and MOZ_MUST_USE.
+// GuardObjectNotifier and the MOZ_* annotations.
 template <typename ExitFunction>
 class ScopeExit {
   ExitFunction mExitFunction;
@@ -314,4 +314,4 @@ BOOL APIENTRY DllMain(HINSTANCE instance, DWORD reason, LPVOID) {
     InitializeCriticalSection(&gStartBitsThread.cs);
   }
   return TRUE;
-}
+}