Avoid macro redefinition error if HAVE_LIBCOMPRESSION
is already defined.

llvm-svn: 357553
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
index 89059f7..60d33cc 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
@@ -37,7 +37,9 @@
 #include "llvm/ADT/StringSwitch.h"
 
 #if defined(__APPLE__)
+#ifndef HAVE_LIBCOMPRESSION
 #define HAVE_LIBCOMPRESSION
+#endif
 #include <compression.h>
 #endif