[gn build] Port d0c973a

Author: llvmgnsyncbot

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

@@ -124,6 +124,7 @@ static_library("Support") {
     "Parallel.cpp",
     "PluginLoader.cpp",
     "PrettyStackTrace.cpp",
+    "ProgramStack.cpp",
     "RISCVAttributeParser.cpp",
     "RISCVAttributes.cpp",
     "RISCVISAUtils.cpp",

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

@@ -71,6 +71,7 @@ unittest("SupportTests") {
     "Path.cpp",
     "PerThreadBumpPtrAllocatorTest.cpp",
     "ProcessTest.cpp",
+    "ProgramStackTest.cpp",
     "ProgramTest.cpp",
     "RISCVAttributeParserTest.cpp",
     "RecyclerTest.cpp",