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/Utility/Log.cpp b/lldb/source/Utility/Log.cpp
index f247124..16396fb 100644
--- a/lldb/source/Utility/Log.cpp
+++ b/lldb/source/Utility/Log.cpp
@@ -28,7 +28,7 @@
 #include <utility> // for pair
 
 #include <assert.h>  // for assert
-#if defined(LLVM_ON_WIN32)
+#if defined(_WIN32)
 #include <process.h> // for getpid
 #else
 #include <unistd.h>