libunwind: Introduce __libunwind_config.h.

Introduce __libunwind_config.h to avoid cross repository circular
dependency with libcxxabi.

llvm-svn: 242642
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 5191fe9509fab84b7681c7ef6f4eceef877d5339
diff --git a/src/AddressSpace.hpp b/src/AddressSpace.hpp
index 4d74129..567cbda 100644
--- a/src/AddressSpace.hpp
+++ b/src/AddressSpace.hpp
@@ -34,7 +34,7 @@
 #include "dwarf2.h"
 #include "Registers.hpp"
 
-#if LIBCXXABI_ARM_EHABI
+#if _LIBUNWIND_ARM_EHABI
 #ifdef __linux__
 
 typedef long unsigned int *_Unwind_Ptr;
@@ -55,7 +55,7 @@
 extern EHTEntry __exidx_start;
 extern EHTEntry __exidx_end;
 #endif // !defined(_LIBUNWIND_IS_BAREMETAL)
-#endif  // LIBCXXABI_ARM_EHABI
+#endif // _LIBUNWIND_ARM_EHABI
 
 #if defined(__CloudABI__) || defined(__FreeBSD__) || defined(__linux__)
 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND && _LIBUNWIND_SUPPORT_DWARF_INDEX
@@ -92,7 +92,7 @@
   uintptr_t       compact_unwind_section;
   uintptr_t       compact_unwind_section_length;
 #endif
-#if LIBCXXABI_ARM_EHABI
+#if _LIBUNWIND_ARM_EHABI
   uintptr_t       arm_section;
   uintptr_t       arm_section_length;
 #endif
@@ -357,7 +357,7 @@
     info.compact_unwind_section_length = dyldInfo.compact_unwind_section_length;
     return true;
   }
-#elif LIBCXXABI_ARM_EHABI
+#elif _LIBUNWIND_ARM_EHABI
  #ifdef _LIBUNWIND_IS_BAREMETAL
   // Bare metal is statically linked, so no need to ask the dynamic loader
   info.arm_section =        (uintptr_t)(&__exidx_start);