What does this PR do?:

Add SFrame V2 parsing as a transparent optimization in the native unwind table loading path. When the profiler loads a shared library, parseDwarfInfo() checks for a .sframe section first via PT_GNU_SFRAME. If present and valid, it parses the SFrame data directly into the existing FrameDesc* table. If absent or invalid, it falls back to the existing .eh_frame DWARF path. Walk-time code is completely unchanged.

Motivation:

SFrame is a simpler ELF section format that directly encodes CFA/FP/RA offsets in flat, binary-searchable tables without requiring a DWARF CFI bytecode interpreter. On modern Linux distros (Fedora 43+, glibc 2.42+, binutils 2.40+), libraries ship .sframe sections alongside .eh_frame. Parsing SFrame is faster than interpreting DWARF opcodes at library load time.

Additional Notes:

• Linux/ELF only. macOS is unaffected (PT_GNU_SFRAME is never found on Mach-O).
• No new user-visible CStack mode. No changes to StackWalker::walkDwarf() or CodeCache::findFrameDesc().
• Both x86_64 and aarch64 supported, including aarch64 GCC vs Clang default frame detection.
• SFrameParser is self-contained (sframe.h/sframe.cpp), depends only on dwarf.h.
• No external dependencies. No build file changes (Gradle auto-discovers new files).
• Comprehensive bounds checking on all pointer arithmetic from the SFrame section.

How to test the change?:

• 20 unit tests in sframe_ut.cpp covering: header validation (magic, version, arch, truncated section, auxhdr_len), FDE loop (empty array, PCMASK skip, empty FDE skip), FRE parsing (SP/FP-based CFA, fixed/per-FRE RA, leaf functions), offset encodings (1B, 2B, 4B), multiple FDEs with sort verification, address translation with non-zero section_offset, FRE bounds overrun recovery, destructor memory safety, and aarch64 default frame detection.
• ./gradlew ddprof-test:testDebug — new SFrame tests pass, existing DWARF tests unaffected.
• ./gradlew ddprof-lib:compileRelease — builds on both Linux and macOS.
• Integration on modern Linux (Fedora 43+): profile a Java app with cstack=dwarf, verify native stacks are collected via the SFrame path.

For Datadog employees:

• If this PR touches code that signs or publishes builds or packages, or handles
  credentials of any kind, I've requested a review from @DataDog/security-design-and-guidance.
• This PR doesn't touch any of that.
• JIRA: [JIRA-XXXX]

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