[llvm-mca] Fix -skip-unsupported-instruction tests on Windows

Builder alerted me to the failing test, attempt #1 in the blind.

Author: peterwaller-arm

llvm/test/tools/llvm-mca/X86/BtVer2/skip-unsupported-instructions-none-remain.s

@@ -1,5 +1,5 @@
-# RUN: not llvm-mca -mtriple=x86_64-unknown-unknown -mcpu=btver2 -skip-unsupported-instructions %s |& FileCheck --check-prefixes=CHECK-ALL,CHECK-SKIP %s
-# RUN: not llvm-mca -mtriple=x86_64-unknown-unknown -mcpu=btver2 %s |& FileCheck --check-prefixes=CHECK-ALL,CHECK-ERROR %s
+# RUN: not llvm-mca -mtriple=x86_64-unknown-unknown -mcpu=btver2 -skip-unsupported-instructions %s 2>&1 | FileCheck --check-prefixes=CHECK-ALL,CHECK-SKIP %s
+# RUN: not llvm-mca -mtriple=x86_64-unknown-unknown -mcpu=btver2 %s 2>&1 | FileCheck --check-prefixes=CHECK-ALL,CHECK-ERROR %s
 
 # Test defends that if all instructions are skipped leaving an empty input, an error is printed.
 

llvm/test/tools/llvm-mca/X86/BtVer2/unsupported-instruction.s

@@ -1,5 +1,5 @@
-# RUN: llvm-mca -mtriple=x86_64-unknown-unknown -mcpu=btver2 -skip-unsupported-instructions -timeline %s |& FileCheck --check-prefix=CHECK-SKIP %s
-# RUN: not llvm-mca -mtriple=x86_64-unknown-unknown -mcpu=btver2 %s |& FileCheck --check-prefix=CHECK-ERROR %s
+# RUN: llvm-mca -mtriple=x86_64-unknown-unknown -mcpu=btver2 -skip-unsupported-instructions -timeline %s 2>&1 | FileCheck --check-prefix=CHECK-SKIP %s
+# RUN: not llvm-mca -mtriple=x86_64-unknown-unknown -mcpu=btver2 %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
 
 # Test checks that unsupported instructions exit with an error, unless -skip-unsupported-instructions is passed, in which case the remaining instructions should be analysed.