[test] Fix tools/gold/X86/comdat-nodeduplicate.ll on non-X86 hosts

[nathanchance]

Summary

When running this test on an aarch64 machine, it fails:

/usr/bin/ld.gold: error: .../test/tools/gold/X86/Output/comdat-nodeduplicate.ll.tmp/ab.lto.o: incompatible target

Specify the elf_x86_64 emulation as all of the other gold plugin tests
do.

[MaskRay]

LGTM.

llvm/test/tools/gold/X86/comdat-nodeduplicate.ll

 ;; Keep __profd_foo in a nodeduplicate comdat, despite a comdat of the same name
 ;; in a previous object file.
 
 ;; Regular LTO
 
 ; RUN: rm -rf %t && split-file %s %t
 ; RUN: llvm-as %t/a.ll -o %t/a.bc
 ; RUN: llvm-as %t/b.ll -o %t/b.bc
 ; RUN: llvm-as %t/c.ll -o %t/c.bc
 
-; RUN: %gold -plugin %llvmshlibdir/LLVMgold%shlibext --plugin-opt=save-temps \
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext --plugin-opt=save-temps \
 ; RUN:   -u foo %t/a.bc --start-lib %t/b.bc --end-lib -o %t/ab
 
 ; RUN: FileCheck %s --check-prefix=RESOL_AB < %t/ab.resolution.txt
 ; RUN: llvm-readelf -x .data %t/ab | FileCheck %s --check-prefix=DATA
 
 ; RESOL_AB: -r={{.*}}b.bc,__profc_foo,pl{{$}}
 
 ;; .data contains a.bc:data. b.bc:data and c.bc:data are discarded.
 ; DATA: 0x[[#%x,]] 01000000 00000000  ........
 
 ;; __profc_foo from c.bc is non-prevailing and thus discarded.
-; RUN: %gold -plugin %llvmshlibdir/LLVMgold%shlibext --plugin-opt=save-temps \
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext --plugin-opt=save-temps \
 ; RUN:   -u foo -u c %t/a.bc --start-lib %t/b.bc %t/c.bc --end-lib -o %t/abc
 ; RUN: FileCheck %s --check-prefix=RESOL_ABC < %t/abc.resolution.txt
 ; RUN: llvm-readelf -x .data %t/abc | FileCheck %s --check-prefix=DATA
 
 ; RESOL_ABC: -r={{.*}}b.bc,__profc_foo,pl{{$}}
 ; RESOL_ABC: -r={{.*}}c.bc,__profc_foo,l{{$}}
 
 ;; ThinLTO
 
 ; RUN: rm -rf %t && split-file %s %t
 ; RUN: opt --module-summary %t/a.ll -o %t/a.bc
 ; RUN: opt --module-summary %t/b.ll -o %t/b.bc
 ; RUN: opt --module-summary %t/c.ll -o %t/c.bc
 
-; RUN: %gold -plugin %llvmshlibdir/LLVMgold%shlibext \
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext \
 ; RUN:   -u foo %t/a.bc --start-lib %t/b.bc %t/c.bc --end-lib -o %t/abc
 ; RUN: llvm-readelf -x .data %t/abc | FileCheck %s --check-prefix=DATA
 
 ;--- a.ll
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 $__profc_foo = comdat nodeduplicate