[RISC-V] Re-enable WriteXorExecute on riscv64 architecture.

[rzsc]

WriteXorExecute is not fully supported on riscv64 architecture yet.
It's been requested to disable it in default CLR configuration for riscv64 architecture in PR #103408.

This issue is created to remain about re-enabling WriteXorExecute on riscv64 architecture when it gets full support.

Part of #84834, cc @dotnet/samsung

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[am11]

@dotnet/samsung, since #100505 was fixed by #115752, shall we turn the default back on? If the latest QEMU still doesn't work with WriteXorExecute, the test executor can now pass the env vars. Assuming it works on riscv64 devices (baremetal) in test lab.

[tomeksowi]

@dotnet/samsung, since #100505 was fixed by #115752, shall we turn the default back on? If the latest QEMU still doesn't work with WriteXorExecute, the test executor can now pass the env vars. Assuming it works on riscv64 devices (baremetal) in test lab.

It fails without it unfortunately, #115752 only clears DOTNET_SYSTEM_GLOBALIZATION variables.

[am11]

It fails without it unfortunately, #115752 only clears DOTNET_SYSTEM_GLOBALIZATION variables.

It was about preserving the other environment vars and clearing the globalization one. I think this is what we wanted to fix this TODO:

runtime/src/coreclr/inc/clrconfigvalues.h

Line 651 in 2787545

// TODO: https://github.com/dotnet/runtime/issues/103465

i.e. QEMU test machine will set DOTNET_EnableWriteXorExecute=0 (which was getting cleared before), physical hardware won't; assuming it works on baremetal.