Fix sanitizer builds with gcc

bin/varnishd/hpack/vhp_gen_hufdec.c

@@ -252,3 +252,11 @@ main(int argc, const char **argv)
 
 	return (0);
 }
+
+#if defined(__SANITIZER)
+int __lsan_is_turned_off(void);
+int __lsan_is_turned_off()
+{
+       return (1);
+}
+#endif

bin/varnishd/mgt/mgt_param.c

@@ -510,7 +510,7 @@ MCF_InitParams(struct cli *cli)
 	low = sysconf(_SC_THREAD_STACK_MIN);
 	MCF_ParamConf(MCF_MINIMUM, "thread_pool_stack", "%jdb", (intmax_t)low);
 
-#if defined(WITH_SANITIZERS)
+#if defined(__SANITIZER)
 	def = 92 * 1024;
 #else
 	def = 48 * 1024;

configure.ac

@@ -267,8 +267,13 @@ AC_ARG_ENABLE(msan,
 	MSAN_FLAGS="-fsanitize=memory")
 
 if test "x$UBSAN_FLAGS$TSAN_FLAGS$ASAN_FLAGS$MSAN_FLAGS" != "x"; then
-	SAN_CFLAGS="-DWITH_SANITIZERS=1 ${UBSAN_FLAGS} ${TSAN_FLAGS} ${ASAN_FLAGS} ${MSAN_FLAGS} -fPIC -fPIE -fno-omit-frame-pointer"
+	SAN_CFLAGS="-D__SANITIZER=1 ${UBSAN_FLAGS} ${TSAN_FLAGS} ${ASAN_FLAGS} ${MSAN_FLAGS} -fPIC -fPIE -fno-omit-frame-pointer"
 	SAN_LDFLAGS="${UBSAN_FLAGS} ${TSAN_FLAGS} ${ASAN_FLAGS} ${MSAN_FLAGS} -pie"
+	case $CC in
+	gcc*)
+		SAN_CFLAGS="${SAN_CFLAGS} -fuse-ld=gold"
+		;;
+	esac
 fi
 AC_SUBST(SAN_CFLAGS)
 AC_SUBST(SAN_LDFLAGS)