Resubmit "Don't include UnixSignals.h from Host."

This was reverted because it breaks the GreenDragon bot, but
the reason for the breakage is lost, so I'm resubmitting this
now so we can find out what the problem is.

llvm-svn: 355528
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index 5fbae52..734f066b 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -49,6 +49,7 @@
 #include "lldb/Symbol/VariableList.h"
 
 #include "lldb/Target/Language.h"
+#include "lldb/Target/Target.h"
 
 #include "AppleDWARFIndex.h"
 #include "DWARFASTParser.h"
@@ -3836,7 +3837,10 @@
     module_spec.GetFileSpec() = m_obj_file->GetFileSpec();
     module_spec.GetSymbolFileSpec() =
         FileSpec(m_obj_file->GetFileSpec().GetPath() + ".dwp");
-    FileSpec dwp_filespec = Symbols::LocateExecutableSymbolFile(module_spec);
+
+    FileSpecList search_paths = Target::GetDefaultDebugFileSearchPaths();
+    FileSpec dwp_filespec =
+        Symbols::LocateExecutableSymbolFile(module_spec, search_paths);
     if (FileSystem::Instance().Exists(dwp_filespec)) {
       m_dwp_symfile = SymbolFileDWARFDwp::Create(GetObjectFile()->GetModule(),
                                                  dwp_filespec);