build: Fix building fuzz binary on on SunOS / illumos

Author: hebasto

src/Makefile.test.include

@@ -277,7 +277,7 @@ FUZZ_SUITE_LD_COMMON += $(LIBBITCOIN_ZMQ) $(ZMQ_LIBS)
 endif
 
 if ENABLE_FUZZ_BINARY
-test_fuzz_fuzz_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(BOOST_CPPFLAGS)
+test_fuzz_fuzz_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(BOOST_CPPFLAGS) $(EVENT_CFLAGS)
 test_fuzz_fuzz_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 test_fuzz_fuzz_LDADD = $(FUZZ_SUITE_LD_COMMON)
 test_fuzz_fuzz_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS) $(PTHREAD_FLAGS)