Allow this test to pass when the source is on a read-only filesystem

llc attempts to create an empty file in the current directory, but
it can't do that on a read-only file system. Send that empty-output
to stdout, which prevents this failure.

Author: Sterling-Augustine

llvm/test/CodeGen/AMDGPU/llvm.amdgcn.global.load.lds.err.ll

@@ -1,7 +1,7 @@
-; RUN: not --crash llc -mtriple=amdgcn -mcpu=gfx810 %s 2>&1 | FileCheck --ignore-case %s
-; RUN: not --crash llc -global-isel -mtriple=amdgcn -mcpu=gfx810 %s 2>&1 | FileCheck --ignore-case %s
-; RUN: not --crash llc -mtriple=amdgcn -mcpu=gfx1100 %s 2>&1 | FileCheck --ignore-case %s
-; RUN: not --crash llc -global-isel -mtriple=amdgcn -mcpu=gfx1100 %s 2>&1 | FileCheck --ignore-case %s
+; RUN: not --crash llc -o - -mtriple=amdgcn -mcpu=gfx810 %s 2>&1 | FileCheck --ignore-case %s
+; RUN: not --crash llc -o - -global-isel -mtriple=amdgcn -mcpu=gfx810 %s 2>&1 | FileCheck --ignore-case %s
+; RUN: not --crash llc -o - -mtriple=amdgcn -mcpu=gfx1100 %s 2>&1 | FileCheck --ignore-case %s
+; RUN: not --crash llc -o - -global-isel -mtriple=amdgcn -mcpu=gfx1100 %s 2>&1 | FileCheck --ignore-case %s
 ;
 ; CHECK: LLVM ERROR: Cannot select