[gn build] Port a9ee8e4

Author: llvmgnsyncbot

llvm/utils/gn/secondary/llvm/lib/Support/BUILD.gn

@@ -154,6 +154,7 @@ static_library("Support") {
     "SuffixTreeNode.cpp",
     "SystemUtils.cpp",
     "TarWriter.cpp",
+    "TextEncoding.cpp",
     "ThreadPool.cpp",
     "TimeProfiler.cpp",
     "Timer.cpp",

llvm/utils/gn/secondary/llvm/unittests/Support/BUILD.gn

@@ -91,6 +91,7 @@ unittest("SupportTests") {
     "SuffixTreeTest.cpp",
     "SwapByteOrderTest.cpp",
     "TarWriterTest.cpp",
+    "TextEncodingTest.cpp",
     "ThreadPool.cpp",
     "ThreadSafeAllocatorTest.cpp",
     "Threading.cpp",