default bsd make compilation does not include use preprocessor flags

tests/tests-c-compiler/check-assembly.sh

@@ -67,7 +67,7 @@ ${AUTOGENERATED}
 
 COMMON_FLAGS= -I.
 CFLAGS = \${COMMON_FLAGS} ${CFLAGS:-} -g -O0
-CPPFLAGS = -DSRCDIR=../${srcdir} ${CODECS_FLAGS}
+CFLAGS += -DSRCDIR=../${srcdir} ${CODECS_FLAGS}
 CXXFLAGS = \${COMMON_FLAGS} ${CXXFLAGS}
 LDFLAGS = ${LDFLAGS:-}
 
@@ -78,7 +78,7 @@ all: compiled-module
 
 check-executable: \$(OBJS)
 	@rm -f *.core
-	\$(CC) \$(CPPFLAGS) \$(CFLAGS) \$(LDFLAGS) -o check-executable \$(OBJS) -lm
+	\$(CC) \$(CFLAGS) \$(LDFLAGS) -o check-executable \$(OBJS) -lm
 
 # Compile the corresponding .asn1 spec.
 compiled-module: ${asn_module} ${abs_top_builddir}/asn1c/asn1c