Revert "[libunwind] Drop the dependency on <algorithm>, add placement new inline"

This reverts commit r352384: this broke on ARM as UnwindCursor.hpp
still has some C++ library dependencies.

llvm-svn: 352427
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 4ecdb70424a7c057bf6858027abc3a0f59454210
diff --git a/src/Unwind-seh.cpp b/src/Unwind-seh.cpp
index 26eb0ef..f55d624 100644
--- a/src/Unwind-seh.cpp
+++ b/src/Unwind-seh.cpp
@@ -49,10 +49,6 @@
 /// Class of foreign exceptions based on unrecognized SEH exceptions.
 static const uint64_t kSEHExceptionClass = 0x434C4E4753454800; // CLNGSEH\0
 
-// libunwind does not and should not depend on C++ library which means that we
-// need our own declaration of global placement new.
-void *operator new(size_t, void*);
-
 /// Exception cleanup routine used by \c _GCC_specific_handler to
 /// free foreign exceptions.
 static void seh_exc_cleanup(_Unwind_Reason_Code urc, _Unwind_Exception *exc) {
diff --git a/src/UnwindCursor.hpp b/src/UnwindCursor.hpp
index 62efe77..497ff84 100644
--- a/src/UnwindCursor.hpp
+++ b/src/UnwindCursor.hpp
@@ -11,6 +11,7 @@
 #ifndef __UNWINDCURSOR_HPP__
 #define __UNWINDCURSOR_HPP__
 
+#include <algorithm>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/src/libunwind.cpp b/src/libunwind.cpp
index cfa9112..a2496a0 100644
--- a/src/libunwind.cpp
+++ b/src/libunwind.cpp
@@ -11,6 +11,10 @@
 
 #include <libunwind.h>
 
+#ifndef NDEBUG
+#include <cstdlib> // getenv
+#endif
+
 #include "libunwind_ext.h"
 #include "config.h"
 
@@ -23,10 +27,6 @@
 
 using namespace libunwind;
 
-// libunwind does not and should not depend on C++ library which means that we
-// need our own declaration of global placement new.
-void *operator new(size_t, void*);
-
 /// internal object to represent this processes address space
 LocalAddressSpace LocalAddressSpace::sThisAddressSpace;