s/LLVM_ON_WIN32/_WIN32/, lldb
                                                                                
LLVM_ON_WIN32 is set exactly with MSVC and MinGW (but not Cygwin) in            
HandleLLVMOptions.cmake, which is where _WIN32 defined too.  Just use the        
default macro instead of a reinvented one.                                      
                                                                                
See thread "Replacing LLVM_ON_WIN32 with just _WIN32" on llvm-dev and cfe-dev.  
No intended behavior change.

llvm-svn: 329697
diff --git a/lldb/source/Core/PluginManager.cpp b/lldb/source/Core/PluginManager.cpp
index a49fbc3..1f02b40 100644
--- a/lldb/source/Core/PluginManager.cpp
+++ b/lldb/source/Core/PluginManager.cpp
@@ -17,7 +17,7 @@
 #include "lldb/Utility/Status.h"
 #include "lldb/Utility/StringList.h" // for StringList
 
-#if defined(LLVM_ON_WIN32)
+#if defined(_WIN32)
 #include "lldb/Host/windows/PosixApi.h" // for PATH_MAX
 #endif