[gn build] Port 6ab034b

Author: llvmgnsyncbot

llvm/utils/gn/secondary/lld/ELF/BUILD.gn

@@ -42,6 +42,7 @@ static_library("ELF") {
     "Arch/SystemZ.cpp",
     "Arch/X86.cpp",
     "Arch/X86_64.cpp",
+    "BPSectionOrderer.cpp",
     "CallGraphSort.cpp",
     "DWARF.cpp",
     "Driver.cpp",