gh-143632: Detect availability of PR_SET_VMA at runtime (fixes build with musl libc)

[sideeffect42]

Building latest Python 3.15.0a8+ on musl-based Linux fails with the following error:

gcc -c -fno-strict-overflow -Wsign-compare -DNDEBUG -g -O3 -Wall    -std=c11 -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wstrict-prototypes -Werror=implicit-function-declaration -fvisibility=hidden  -I./Include/internal -I./Include/internal/mimalloc  -I. -I./Include    -DPy_BUILD_CORE -o Objects/obmalloc.o Objects/obmalloc.c
In file included from ./Include/internal/pycore_mmap.h:16,
                 from Objects/obmalloc.c:5:
/usr/include/sys/prctl.h:88:8: error: redefinition of 'struct prctl_mm_map'
   88 | struct prctl_mm_map {
      |        ^~~~~~~~~~~~
In file included from ./Include/internal/pycore_mmap.h:15:
/usr/include/linux/prctl.h:134:8: note: originally defined here
  134 | struct prctl_mm_map {
      |        ^~~~~~~~~~~~
make: *** [Makefile:3388: Objects/obmalloc.o] Error 1

This is due to Python including both <linux/prctl.h> and <sys/prctl.h> (which on glibc imports the definitions from <linux/prctl.h> and on musl includes all the definitions itself).
Given that Python is not the Linux kernel, <sys/prctl.h> should be included.

Another issue of the previous implementation and the configure check was that the _PyAnnotateMemoryMap() function would only be enabled if the linux-headers on the build host are recent enough to contain the PR_SET_VMA_ANON_NAME macro.

However the resulting binaries might be run on older kernels lacking the functionality or be built on older systems but run on newer kernels.

With this patch, the function is always enabled and the magic numbers are included with Python, so that the prctl() is always executed and feature detection is essentially done at runtime.

When run on a kernel too old to support PR_SET_VMA_ANON_NAME, mmap.mmap.set_name() will silently do nothing.
When the kernel is new enough but CONFIG_ANON_VMA_NAME is not enabled, mmap.mmap.set_name() will raise an OSError, e.g.:

>>> mm.set_name("hello")
Traceback (most recent call last):
  File "<python-input-5>", line 1, in <module>
    mm.set_name("hello")
    ~~~~~~~~~~~^^^^^^^^^
OSError: [Errno 22] Invalid argument

• Issue: failure building Python 3.15.0a3 on Alpine #143632

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