Windows ARM64 (aarch64-pc-windows-msvc) doesn't have native profiling
support in the background hang monitor. Add it to the list of platforms
that use DummySampler, alongside Linux musl and other unsupported targets.

Part of Windows ARM64 build support: servo#42312

std::process::Command cannot be reused after calling .output() because
it consumes the command's internal state. The previous code would create
a Command, test it with try_python_command(), and then try to return the
same Command - but by then the command was already consumed.

This refactors try_python_command() to:
1. Take program name and args as parameters
2. Only test if the command works (returning Result<(), String>)
3. Create a FRESH Command in find_python() after confirming it works

Part of Windows ARM64 build support: servo#42312

std::process::Command cannot be reused after calling .output() because
it consumes the command's internal state. The previous code would create
a Command, test it with try_python_command(), and then try to return the
same Command - but by then the command was already consumed.

This refactors try_python_command() to:
1. Take program name and args as parameters
2. Only test if the command works (returning Result<(), String>)
3. Create a FRESH Command in find_python() after confirming it works

Part of Windows ARM64 build support: servo#42312

Signed-off-by: npiesco <[email protected]>

Windows ARM64 (aarch64-pc-windows-msvc) doesn't have native profiling
support in the background hang monitor. Add it to the list of platforms
that use DummySampler, alongside Linux musl and other unsupported targets.

Part of Windows ARM64 build support: servo#42312

Signed-off-by: npiesco <[email protected]>

Windows ARM64 (aarch64-pc-windows-msvc) doesn't have native profiling
support in the background hang monitor. Add it to the list of platforms
that use DummySampler, alongside Linux musl and other unsupported targets.

Part of Windows ARM64 build support: servo#42312

Signed-off-by: npiesco <[email protected]>

Windows ARM64 (aarch64, MSVC) does not support native profiling. PR
updates platform configuration to route Windows ARM64 to DummySampler,
aligning it with other unsupported targets (e.g., Linux musl) and fixing
build compatibility.

PR #42312
- Updates platform configuration + conditional compilation
- Background hang monitor (lib.rs) now selects DummySampler on Windows
ARM64
- Uses DummySampler as SamplerImpl for aarch64 Windows

build/compatibility fix only.

---------

Signed-off-by: npiesco <[email protected]>