Fix haiku and illumos x64 builds

[am11]

Regarding _X, the alternative was to rename it to PAL_X everywhere but that turned it into a 1400+ lines of change; can apply if needed.

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[am11]

@jkotas can this be merged?

[Copilot]

Pull request overview

This PR makes a set of platform-specific tweaks to restore/build successfully on Haiku and illumos/SunOS x64, primarily by adjusting atomic usage, header/feature guards, and build-time configuration for crashreport.

Changes:

• Add Haiku+clang-specific atomic load/store usage in minipal_getpagesize.
• Tighten Sysctl-dependent networking statistics compilation guards for platforms missing sys/sysctl.h.
• Address SunOS _X macro collisions in corehost PAL headers, and add crashreport CMake configure-time feature detection.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/native/minipal/ospagesize.c	Uses clang __c11_atomic_* on Haiku to cache page size.
src/native/libs/System.Native/pal_networkstatistics.c	Gates route/sysctl-based implementations on HAVE_SYS_SYSCTL_H.
src/native/corehost/hostmisc/pal.unix.c	Adds DT_* fallback values and switches /proc/self/maps scanning to a runtime-built sscanf format.
src/native/corehost/hostmisc/pal.h	Introduces PAL_X and redefines _X after generated config includes, with a SunOS workaround.
src/coreclr/jit/gentree.cpp	Suppresses a SunOS GCC warning around CanAssignFrom in a local-load fast-path.
src/coreclr/debug/crashreport/inproccrashreporter.cpp	Includes generated config.h and uses feature macros to gate headers.
src/coreclr/debug/crashreport/configure.cmake	Adds CMake checks and generates config.h.
src/coreclr/debug/crashreport/config.h.in	Template for generated crashreport feature macros.
src/coreclr/debug/crashreport/CMakeLists.txt	Wires crashreport configure.cmake and binary include dir into the build.

Suppressed comments (1)

src/native/corehost/hostmisc/pal.unix.c:385

• The snprintf that builds fmt is invariant across loop iterations but is currently executed once per /proc/self/maps line. It can be moved before the while loop to avoid repeated work in what can be a fairly large file.

        // Build the sscanf format dynamically to safely handle parenthesized PATH_MAX values on some platforms (like Haiku)
        char fmt[64];
        snprintf(fmt, sizeof(fmt), "%%*p-%%*p %%*[-rwxsp] %%*p %%*[:0-9a-f] %%*d %%%ds\n", PATH_MAX);

        char buf[PATH_MAX + 1]; // + 1 for the NUL terminator
        if (sscanf(line, fmt, buf) == 1)

[am11]

@jkotas, thanks!