[gn build] Port 1425d75

Author: llvmgnsyncbot

llvm/utils/gn/secondary/llvm/lib/Target/X86/BUILD.gn

@@ -90,7 +90,6 @@ static_library("LLVMX86CodeGen") {
     "X86CmovConversion.cpp",
     "X86CodeGenPassBuilder.cpp",
     "X86CompressEVEX.cpp",
-    "X86DiscriminateMemOps.cpp",
     "X86DomainReassignment.cpp",
     "X86DynAllocaExpander.cpp",
     "X86ExpandPseudo.cpp",
@@ -110,7 +109,6 @@ static_library("LLVMX86CodeGen") {
     "X86ISelLoweringCall.cpp",
     "X86IndirectBranchTracking.cpp",
     "X86IndirectThunks.cpp",
-    "X86InsertPrefetch.cpp",
     "X86InsertWait.cpp",
     "X86InstCombineIntrinsic.cpp",
     "X86InstrFMA3Info.cpp",