Use CloseOnExec in Platform::PutFile

[labath]

Summary

This does not fix any outstanding issue that I know of, but there is no reason these files should
_not_ have CloseOnExec.

[emaste]

LGTM

lldb/trunk/source/Target/Platform.cpp

Platform::PutFile (const FileSpec& source,
                    const FileSpec& destination,
                    uint32_t uid,
                    uint32_t gid)
 {
     Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_PLATFORM));
     if (log)
         log->Printf("[PutFile] Using block by block transfer....\n");
 
-    uint32_t source_open_options = File::eOpenOptionRead;
+    uint32_t source_open_options = File::eOpenOptionRead | File::eOpenOptionCloseOnExec;
     if (source.GetFileType() == FileSpec::eFileTypeSymbolicLink)
         source_open_options |= File::eOpenoptionDontFollowSymlinks;
 
     File source_file(source, source_open_options, lldb::eFilePermissionsUserRW);
     Error error;
     uint32_t permissions = source_file.GetPermissions(error);
     if (permissions == 0)
         permissions = lldb::eFilePermissionsFileDefault;
 
     if (!source_file.IsValid())
         return Error("PutFile: unable to open source file");
     lldb::user_id_t dest_file = OpenFile (destination,
                                           File::eOpenOptionCanCreate |
                                           File::eOpenOptionWrite |
-                                          File::eOpenOptionTruncate,
+                                          File::eOpenOptionTruncate |
+                                          File::eOpenOptionCloseOnExec,
                                           permissions,
                                           error);
     if (log)
         log->Printf ("dest_file = %" PRIu64 "\n", dest_file);
 
     if (error.Fail())
         return error;
     if (dest_file == UINT64_MAX)