Merge unsupported object tests

Author: arsenm

llvm/test/CodeGen/AArch64/nonwindows-coff-mc-error.ll

@@ -1,10 +1,14 @@
-; RUN: not llc -mtriple=aarch64-pc-unknown-xcoff -filetype=null %s 2>&1 | FileCheck %s
-; RUN: not llc -mtriple=aarch64-pc-unknown-goff -filetype=null %s 2>&1 | FileCheck %s
+; RUN: not llc -mtriple=aarch64-pc-unknown-xcoff -filetype=null %s 2>&1 | FileCheck -check-prefix=OBJFORMAT %s
+; RUN: not llc -mtriple=aarch64-pc-unknown-goff -filetype=null %s 2>&1 | FileCheck -check-prefix=OBJFORMAT %s
+
+; RUN: not llc -mtriple=aarch64-unknown-linux-coff -filetype=null %s 2>&1 | FileCheck -check-prefix=MCINIT %s
+; CHECK: LLVM ERROR: cannot initialize MC for non-Windows COFF object files
 
 ; Make sure there is no crash or assert with unexpected object
 ; formats.
 
-; CHECK: LLVM ERROR: unsupported object format
+; OBJFORMAT: LLVM ERROR: unsupported object format
+; MCINIT: LLVM ERROR: cannot initialize MC for non-Windows COFF object files
 define void @foo() {
   ret void
 }