[BOLT][test] Replace /dev/null with temp file (#73485)
NFC processing time script identifies tests by output filename.
When `/dev/null` is used as output filename, we're unable to tell the
source test, and the reports are unhelpful.
Replace `/dev/null/` with `%t.null` which resolves the issue.
diff --git a/bolt/test/RISCV/reloc-branch.s b/bolt/test/RISCV/reloc-branch.s
index 4399114..6a8b5a2 100644
--- a/bolt/test/RISCV/reloc-branch.s
+++ b/bolt/test/RISCV/reloc-branch.s
@@ -1,5 +1,5 @@
// RUN: %clang %cflags -o %t %s
-// RUN: llvm-bolt --print-cfg --print-only=_start -o /dev/null %t \
+// RUN: llvm-bolt --print-cfg --print-only=_start -o %t.null %t \
// RUN: | FileCheck %s
.text
