[gn build] Port cfbed2c

Author: llvmgnsyncbot

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

@@ -129,6 +129,7 @@ static_library("Support") {
     "ScaledNumber.cpp",
     "ScopedPrinter.cpp",
     "Signposts.cpp",
+    "SipHash.cpp",
     "SlowDynamicAPInt.cpp",
     "SmallPtrSet.cpp",
     "SmallVector.cpp",

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

@@ -78,6 +78,7 @@ unittest("SupportTests") {
     "ScaledNumberTest.cpp",
     "ScopedPrinterTest.cpp",
     "SignalsTest.cpp",
+    "SipHashTest.cpp",
     "SourceMgrTest.cpp",
     "SpecialCaseListTest.cpp",
     "SuffixTreeTest.cpp",