Make CoreCLR compatible with W^X

[jkotas]

https://en.wikipedia.org/wiki/W%5EX

[tannergooding]

It looks like this will be required to support the new Apple Silicon (Arm on macOS): mono/mono#20014

[lambdageek]

It looks like this will be required to support the new Apple Silicon (Arm on macOS): mono/mono#20014

The relevant Apple guidance is https://developer.apple.com/documentation/apple_silicon/porting_just-in-time_compilers_to_apple_silicon

New memory pages start out as readable and executable (R-X) by default. Calling pthread_jit_write_protect_np with the value false removes the executable permission for the current thread and adds the writable permission (RW-). The change applies only to the current thread; other threads that write to the JIT memory region must similarly call the function before writing any data. When write protections are disabled, the thread may write instructions to the JIT memory page, but it may not execute those instructions.

[jkotas]

Duplicate of #50391