Revert "[lldb] Use nullptr instead of 0 or NULL (NFC)"

This reverts commit 913457acf07be7f22d71ac41ad1076517d7f45c6.

It again broke builds on Windows:

  lldb/source/Host/common/HostNativeThreadBase.cpp(37,14): error:
  assigning to 'lldb::thread_result_t' (aka 'unsigned int') from
  incompatible type 'std::nullptr_t'

1 files changed, 3 insertions, 3 deletions

diff --git a/lldb/source/Host/common/HostNativeThreadBase.cpp b/lldb/source/Host/common/HostNativeThreadBase.cpp
index e7966d9ebaa5..b15160b143ca 100644
--- a/lldb/source/Host/common/HostNativeThreadBase.cpp
+++ b/lldb/source/Host/common/HostNativeThreadBase.cpp
@@ -18,7 +18,7 @@ using namespace lldb;
 using namespace lldb_private;
 
 HostNativeThreadBase::HostNativeThreadBase(thread_t thread)
-    : m_thread(thread), m_result(nullptr) {}
+    : m_thread(thread), m_result(0) {}
 
 lldb::thread_t HostNativeThreadBase::GetSystemHandle() const {
   return m_thread;
@@ -34,7 +34,7 @@ bool HostNativeThreadBase::IsJoinable() const {
 
 void HostNativeThreadBase::Reset() {
   m_thread = LLDB_INVALID_HOST_THREAD;
-  m_result = nullptr;
+  m_result = 0;
 }
 
 bool HostNativeThreadBase::EqualsThread(lldb::thread_t thread) const {
@@ -44,7 +44,7 @@ bool HostNativeThreadBase::EqualsThread(lldb::thread_t thread) const {
 lldb::thread_t HostNativeThreadBase::Release() {
   lldb::thread_t result = m_thread;
   m_thread = LLDB_INVALID_HOST_THREAD;
-  m_result = nullptr;
+  m_result = 0;
 
   return result;
 }