Force libcompression calls to be enabled when building on Darwin
systems.  It has been available in the OS over over three years
now.  If lldb doesn't link against -lcompression, it should be an
error.

Allocate a scratch buffer for libcompression to use when decoding
packets, instead of it having to allocate & free one on every call.

Fix a typeo with the size of the buffer that compression_decode_buffer()
is expanding into.

<rdar://problem/41601084> 

llvm-svn: 349563
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
index 92bde03..1e12ea6 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
@@ -37,7 +37,8 @@
 
 #include "llvm/ADT/StringSwitch.h"
 
-#if defined(HAVE_LIBCOMPRESSION)
+#if defined(__APPLE__)
+#define HAVE_LIBCOMPRESSION
 #include <compression.h>
 #endif