[gn build] Port d1bb8d6

Author: llvmgnsyncbot

llvm/utils/gn/secondary/lldb/source/Host/BUILD.gn

@@ -49,6 +49,7 @@ static_library("Host") {
     "common/UDPSocket.cpp",
     "common/XML.cpp",
     "common/ZipFileResolver.cpp",
+    "posix/Support.cpp",
   ]
 
   if (lldb_enable_libedit) {