Merge bitcoin#25492: util: remove MSVC warning pragmas

d8f8f78 util: remove MSVC warning pragmas (fanquake)

Pull request description:

  4786 - I don't think this exists any more?
  4805 - Is already defined (globally) there.

  Dropped 4717 and 4804, as it seems they are no-longer supressing
  anything.

  See:
  https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warnings-c4000-c5999.

ACKs for top commit:
  hebasto:
    ACK d8f8f78, build [log](https://api.cirrus-ci.com/v1/task/6088784285532160/logs/build.log) is free of warnings.

Tree-SHA512: c8ac4585799996960ea099b2c5337e7bb577152eec2e9543cc459c56f42f7a36fc4dcd7faec2fa4ac159a4ae27859650ccfd96bbf94b94dbd1cbea638560a24f

src/util/system.cpp

@@ -53,13 +53,6 @@
 
 #else
 
-#ifdef _MSC_VER
-#pragma warning(disable:4786)
-#pragma warning(disable:4804)
-#pragma warning(disable:4805)
-#pragma warning(disable:4717)
-#endif
-
 #include <codecvt>
 
 #include <io.h> /* for _commit */