[Driver][test] Ignore %clang exit code for -mcpu=native tests

They may be either 0 or 1, depending whether `--target=` specifies a
native target.

Author: MaskRay

clang/test/Driver/aarch64-mcpu.c

@@ -19,7 +19,8 @@
 
 // We cannot check much for -mcpu=native, but it should be replaced by either generic or a valid
 // Arm cpu string, depending on the host.
-// RUN: not %clang --target=arm64 -mcpu=native -### -c %s 2>&1 | FileCheck -check-prefix=ARM64-NATIVE %s
+// RUN: %clang --target=arm64 -mcpu=native -### -c %s 2> %t.err || true
+// RUN: FileCheck --input-file=%t.err -check-prefix=ARM64-NATIVE %s
 // ARM64-NATIVE-NOT: "-cc1"{{.*}} "-triple" "arm64{{.*}}" "-target-cpu" "native"
 
 // RUN: %clang --target=arm64-apple-ios -arch arm64 -### -c %s 2>&1 | FileCheck -check-prefix=ARM64-IOS %s

clang/test/Driver/ppc-cpus.c

@@ -2,7 +2,8 @@
 // MCPU_PPC64: "-target-cpu" "ppc64"
 
 /// We cannot check much for -mcpu=native, but it should be replaced by a CPU name.
-// RUN: %clang -### -c --target=powerpc64 %s -mcpu=native 2>&1 | FileCheck --check-prefix=MCPU_NATIVE %s
+// RUN: %clang -### -c --target=powerpc64 %s -mcpu=native 2> %t.err || true
+// RUN: FileCheck --input-file=%t.err -check-prefix=MCPU_NATIVE %s
 // MCPU_NATIVE-NOT: "-target-cpu" "native"
 
 /// Check that we are passing unknown mcpu options to the backend so an error

clang/test/Driver/riscv-cpus.c

@@ -21,7 +21,8 @@
 // MCPU-SYNTACORE-SCR1-MAX: "-target-abi" "ilp32"
 
 // We cannot check much for -mcpu=native, but it should be replaced by a valid CPU string.
-// RUN: not %clang --target=riscv64 -### -c %s 2>&1 -mcpu=native | FileCheck -check-prefix=MCPU-NATIVE %s
+// RUN: %clang --target=riscv64 -### -c %s -mcpu=native 2> %t.err || true
+// RUN: FileCheck --input-file=%t.err -check-prefix=MCPU-NATIVE %s
 // MCPU-NATIVE-NOT: "-target-cpu" "native"
 
 // RUN: %clang --target=riscv32 -### -c %s 2>&1 -mtune=rocket-rv32 | FileCheck -check-prefix=MTUNE-ROCKET32 %s