Remove no-op function pointer null checks, NFC

Null-checking functions which aren't marked weak_import is a no-op
(the compiler rewrites the check to 'true'), regardless of whether a
library providing its definition is weak-linked. If the deployment
target is greater than the minimum requirement, the availability markup
on APIs does not lower to weak_import.

Remove no-op null checks to clean up the code and silence warnings.

Differential Revision: https://reviews.llvm.org/D40812

llvm-svn: 319936
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
index 0078a14..e79f5d0 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
@@ -1022,10 +1022,7 @@
   std::string avail_name;
 
 #if defined(HAVE_LIBCOMPRESSION)
-  // libcompression is weak linked so test if compression_decode_buffer() is
-  // available
-  if (compression_decode_buffer != NULL &&
-      avail_type == CompressionType::None) {
+  if (avail_type == CompressionType::None) {
     for (auto compression : supported_compressions) {
       if (compression == "lzfse") {
         avail_type = CompressionType::LZFSE;
@@ -1037,10 +1034,7 @@
 #endif
 
 #if defined(HAVE_LIBCOMPRESSION)
-  // libcompression is weak linked so test if compression_decode_buffer() is
-  // available
-  if (compression_decode_buffer != NULL &&
-      avail_type == CompressionType::None) {
+  if (avail_type == CompressionType::None) {
     for (auto compression : supported_compressions) {
       if (compression == "zlib-deflate") {
         avail_type = CompressionType::ZlibDeflate;
@@ -1064,10 +1058,7 @@
 #endif
 
 #if defined(HAVE_LIBCOMPRESSION)
-  // libcompression is weak linked so test if compression_decode_buffer() is
-  // available
-  if (compression_decode_buffer != NULL &&
-      avail_type == CompressionType::None) {
+  if (avail_type == CompressionType::None) {
     for (auto compression : supported_compressions) {
       if (compression == "lz4") {
         avail_type = CompressionType::LZ4;
@@ -1079,10 +1070,7 @@
 #endif
 
 #if defined(HAVE_LIBCOMPRESSION)
-  // libcompression is weak linked so test if compression_decode_buffer() is
-  // available
-  if (compression_decode_buffer != NULL &&
-      avail_type == CompressionType::None) {
+  if (avail_type == CompressionType::None) {
     for (auto compression : supported_compressions) {
       if (compression == "lzma") {
         avail_type = CompressionType::LZMA;