macOS: portability + RPC in-proc fallback

[SoumojitDalui]

TL;DR

This PR adds macOS support (including Apple Silicon) while preserving Linux behavior. It vendors yaml-cpp, gates Linux-only features behind build flags, and adds an in-process RPC fallback so the existing CI/tests run reliably on macOS.

Details

CMake / Dependencies

• Make libdpdk optional so macOS can configure without it.
• Add Homebrew include/lib discovery (/opt/homebrew and /usr/local).
• Vendor yaml-cpp from dependencies/yaml-cpp and link yaml-cpp::yaml-cpp into txlog, executables, and tests.
• Add ENABLE_ERPC / ENABLE_RPC toggles; default ENABLE_ERPC=OFF on macOS; compile/link eRPC only when enabled.
• Avoid linking Linux-only libs on macOS (-lnuma, -lrt, and -lboost_system).

NUMA (Linux kept, macOS stubbed)

• Add src/compat/numa.h and use it on macOS so code including <numa.h> compiles without libnuma.

macOS / Apple Silicon portability

• Guard Linux-only headers (<sys/sysinfo.h>).
• Replace fdatasync() with fsync() on macOS.
• Handle missing MADV_HUGEPAGE.
• Use malloc/malloc.h on macOS where malloc.h is unavailable.
• Replace memalign() with posix_memalign() on macOS.
• Guard x86-only headers/instructions and add ARM-friendly fallbacks for “pause/yield” and cycle counters (mach_absolute_time() / cntvct_el0).

RPC: in-process fallback for macOS restrictions

• Add src/rrr/rpc/inproc_transport.* and integrate it into client/server.
• If bind() fails with EPERM, server registers an in-process endpoint and clients connect via socketpair() (no TCP bind/listen).
• Set SO_NOSIGPIPE on macOS sockets to prevent SIGPIPE termination.
• Skip TCP keepalive configuration for in-process connections.

Reactor fixes

• Reduce kqueue wait timeout.
• Fix coroutine cleanup edge case and a timeout boundary condition.
• Make Fiber::sleep(0) return immediately.