Comment -DNDEBUG in head after r339436 when head was switched

from 12.0-ALPHA10 to 13.0-CURRENT.  This edit was a mistake,
and should have been applied to stable/12 upon branching, not
head.

Reported by:	jbeich, dim
Sponsored by:	The FreeBSD Foundation

lib/clang/llvm.build.mk

@@ -17,7 +17,7 @@ CFLAGS+=	-I${LLVM_SRCS}/include
 CFLAGS+=	-DLLVM_BUILD_GLOBAL_ISEL
 CFLAGS+=	-D__STDC_LIMIT_MACROS
 CFLAGS+=	-D__STDC_CONSTANT_MACROS
-CFLAGS+=	-DNDEBUG
+#CFLAGS+=	-DNDEBUG
 
 TARGET_ARCH?=	${MACHINE_ARCH}
 BUILD_ARCH?=	${MACHINE_ARCH}