Remove redundant `#if NET` directives

[xtqqczze]

The repository contains redundant #if NET conditional compilation directives. This check is unnecessary when a file is only compiled in a .NET (not NET Standard/Framework) build configuration. In any .NET build the NET symbol will always be defined, making the #if NET block effectively always true and thus redundant.

Example

In HuffmanDecodingException.cs, the following code is wrapped in an unnecessary #if NET directive:

runtime/src/libraries/Common/src/System/Net/Http/aspnetcore/Http2/Hpack/HuffmanDecodingException.cs

Lines 22 to 24 in e399fff

	#if NET
	[Obsolete(Obsoletions.LegacyFormatterImplMessage, DiagnosticId = Obsoletions.LegacyFormatterImplDiagId, UrlFormat = Obsoletions.SharedUrlFormat)]
	#endif

However, this file is only compiled in the NetCoreAppCurrent build configuration:

runtime/src/libraries/System.Net.Http/src/System.Net.Http.csproj

Line 4 in e399fff

<TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-linux;$(NetCoreAppCurrent)-osx;$(NetCoreAppCurrent)-freebsd;$(NetCoreAppCurrent)-maccatalyst;$(NetCoreAppCurrent)-ios;$(NetCoreAppCurrent)-tvos;$(NetCoreAppCurrent)-browser;$(NetCoreAppCurrent)-wasi;$(NetCoreAppCurrent)-illumos;$(NetCoreAppCurrent)-solaris;$(NetCoreAppCurrent)-haiku;$(NetCoreAppCurrent)-android;$(NetCoreAppCurrent)</TargetFrameworks>

Since that configuration targets .NET 10, the NET symbol is always defined, and the directive can be safely removed.

[jkotas]

Are you interested in submitting a PR to clean this up?

However, this file is only compiled in the NetCoreAppCurrent build configuration:

The file that you have linked it shared between dotnet/runtime and dotnet/aspnetcore, so you have to check in both repos whether the ifdef is actually unnecessary.

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[xtqqczze]

Are you interested in submitting a PR to clean this up?

@agocke I submitted the issue with @copilot in mind, to cleanup after #118363

[jkotas]

We can give it a try...