[libunwind] Fix a few libunwind includes

[ldionne]

Summary

In UnwindCursor.hpp, include config.h before checking
_LIBUNWIND_SUPPORT_SEH_UNWIND.

Include libunwind_ext.h for UNW_STEP_SUCCESS.

[rprichard]

On second thought, maybe I don't actually need this change, and the includes still seem like a mess in libunwind. Maybe it makes more sense to do a larger revision eventually.

[compnerd]

This seems relatively harmless, not sure if its valuable though.

[MaskRay]

... so that it no longer shows on my review queue. I think this is still worth doing, especially the weird include places in UnwindCursor.hpp might confuse readers.

[ldionne]

Commandeering to rebase and land.

[ldionne]

Here we go -- rebase onto main. I'll land once CI is green.

[phosek]

LGTM

libunwind/src/CompactUnwinder.hpp

 
 #include <stdint.h>
 #include <stdlib.h>
 
 #include <libunwind.h>
 #include <mach-o/compact_unwind_encoding.h>
 
 #include "Registers.hpp"
+#include "libunwind_ext.h"
 
 #define EXTRACT_BITS(value, mask)                                              \
   ((value >> __builtin_ctz(mask)) & (((1 << __builtin_popcount(mask))) - 1))
 
 namespace libunwind {
 
 #if defined(_LIBUNWIND_TARGET_I386)
 /// CompactUnwinder_x86 uses a compact unwind info to virtually "step" (aka

libunwind/src/DwarfInstructions.hpp

 
 #ifndef __DWARF_INSTRUCTIONS_HPP__
 #define __DWARF_INSTRUCTIONS_HPP__
 
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 
-#include "dwarf2.h"
-#include "Registers.hpp"
 #include "DwarfParser.hpp"
+#include "Registers.hpp"
 #include "config.h"
+#include "dwarf2.h"
+#include "libunwind_ext.h"
 
 
 namespace libunwind {
 
 
 /// DwarfInstructions maps abstract DWARF unwind instructions to a particular
 /// architecture
 template <typename A, typename R>

libunwind/src/UnwindCursor.hpp

 #if defined(_LIBUNWIND_TARGET_LINUX) &&                                        \
     (defined(_LIBUNWIND_TARGET_AARCH64) || defined(_LIBUNWIND_TARGET_S390X))
 #include <sys/syscall.h>
 #include <sys/uio.h>
 #include <unistd.h>
 #define _LIBUNWIND_CHECK_LINUX_SIGRETURN 1
 #endif
 
+#include "AddressSpace.hpp"
+#include "CompactUnwinder.hpp"
+#include "config.h"
+#include "DwarfInstructions.hpp"
+#include "EHHeaderParser.hpp"
+#include "libunwind.h"
+#include "libunwind_ext.h"
+#include "Registers.hpp"
+#include "RWMutex.hpp"
+#include "Unwind-EHABI.h"
+
 #if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)
 // Provide a definition for the DISPATCHER_CONTEXT struct for old (Win7 and
 // earlier) SDKs.
 // MinGW-w64 has always provided this struct.
   #if defined(_WIN32) && defined(_LIBUNWIND_TARGET_X86_64) && \
       !defined(__MINGW32__) && VER_PRODUCTBUILD < 8000
 struct _DISPATCHER_CONTEXT {
   ULONG64 ControlPc;

 };
 
 extern "C" _Unwind_Reason_Code __libunwind_seh_personality(
     int, _Unwind_Action, uint64_t, _Unwind_Exception *,
     struct _Unwind_Context *);
 
 #endif
 
-#include "config.h"
-
-#include "AddressSpace.hpp"
-#include "CompactUnwinder.hpp"
-#include "config.h"
-#include "DwarfInstructions.hpp"
-#include "EHHeaderParser.hpp"
-#include "libunwind.h"
-#include "Registers.hpp"
-#include "RWMutex.hpp"
-#include "Unwind-EHABI.h"
-
 namespace libunwind {
 
 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
 /// Cache of recently found FDEs.
 template <typename A>
 class _LIBUNWIND_HIDDEN DwarfFDECache {
   typedef typename A::pint_t pint_t;
 public: