Use CPU_CHECK_PLACEHOLDER instead of FileCheck

If %CPU_RUN_PLACEHOLDER is substituted to `echo', FileCheck will not
match.

Signed-off-by: Andrew Savonichev <andrew.savonichev@intel.com>

sycl/test/basic_tests/subdevice_pi.cpp

@@ -1,7 +1,7 @@
 // RUN: %clangxx -fsycl -fsycl-targets=%sycl_triple %s -o %t.out
-// RUN: %CPU_RUN_PLACEHOLDER SYCL_PI_TRACE=1 %t.out separate equally | FileCheck %s --check-prefix CHECK-SEPARATE
-// RUN: %CPU_RUN_PLACEHOLDER SYCL_PI_TRACE=1 %t.out shared equally | FileCheck %s --check-prefix CHECK-SHARED --implicit-check-not piContextCreate --implicit-check-not piMemBufferCreate
-// RUN: %CPU_RUN_PLACEHOLDER SYCL_PI_TRACE=1 %t.out fused  equally | FileCheck %s --check-prefix CHECK-FUSED --implicit-check-not piContextCreate --implicit-check-not piMemBufferCreate
+// RUN: %CPU_RUN_PLACEHOLDER SYCL_PI_TRACE=1 %t.out separate equally %CPU_CHECK_PLACEHOLDER --check-prefix CHECK-SEPARATE
+// RUN: %CPU_RUN_PLACEHOLDER SYCL_PI_TRACE=1 %t.out shared equally %CPU_CHECK_PLACEHOLDER --check-prefix CHECK-SHARED --implicit-check-not piContextCreate --implicit-check-not piMemBufferCreate
+// RUN: %CPU_RUN_PLACEHOLDER SYCL_PI_TRACE=1 %t.out fused  equally %CPU_CHECK_PLACEHOLDER --check-prefix CHECK-FUSED --implicit-check-not piContextCreate --implicit-check-not piMemBufferCreate
 //
 // Intel OpenCL CPU Runtime supports device partition on all (multi-core)
 // platforms. Other devices may not support this.