[NFC] [scudo] syntax-check DCHECK arguments if DCHECK is off

This is a widespread technique, used in at least:

* ABSL: https://github.com/abseil/abseil-cpp/blob/master/absl/log/internal/check_op.h#L52
* Chromium: https://source.chromium.org/chromium/chromium/src/+/main:base/check.h;l=185?q=DCHECK%20f:base&ss=chromium
* Android: https://cs.android.com/android/platform/superproject/+/master:system/libbase/include/android-base/logging.h;drc=bda7f0a0cc945c860713a1dc497919f17fad1651;l=321

Reviewed By: Chia-hungDuan, vitalybuka

Differential Revision: https://reviews.llvm.org/D141713