Fix unittest build error

src/Makefile.am

@@ -128,7 +128,8 @@ nghttpx_unittest_SOURCES = shrpx-unittest.cc \
 	shrpx_config_test.cc shrpx_config_test.h \
 	http2_test.cc http2_test.h \
 	util_test.cc util_test.h \
-	nghttp2_gzip_test.c nghttp2_gzip_test.h
+	nghttp2_gzip_test.c nghttp2_gzip_test.h \
+	nghttp2_gzip.c nghttp2_gzip.h
 nghttpx_unittest_CPPFLAGS = ${AM_CPPFLAGS}\
 	 -DNGHTTP2_TESTS_DIR=\"$(top_srcdir)/tests\"
 nghttpx_unittest_LDFLAGS = -static

src/nghttp2_gzip_test.h

@@ -25,6 +25,14 @@
 #ifndef NGHTTP2_GZIP_TEST_H
 #define NGHTTP2_GZIP_TEST_H
 
+#ifdef  __cplusplus
+extern "C" {
+#endif
+
 void test_nghttp2_gzip_inflate(void);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* NGHTTP2_GZIP_TEST_H */

src/shrpx-unittest.cc

@@ -33,6 +33,7 @@
 #include "shrpx_config_test.h"
 #include "http2_test.h"
 #include "util_test.h"
+#include "nghttp2_gzip_test.h"
 
 static int init_suite1(void)
 {

tests/Makefile.am

@@ -37,14 +37,13 @@ OBJECTS = main.c nghttp2_pq_test.c nghttp2_map_test.c nghttp2_queue_test.c \
 	nghttp2_session_test.c \
 	nghttp2_hd_test.c \
 	nghttp2_npn_test.c \
-	nghttp2_gzip_test.c \
 	nghttp2_helper_test.c \
 	nghttp2_buf_test.c
 
 HFILES = nghttp2_pq_test.h nghttp2_map_test.h nghttp2_queue_test.h \
 	nghttp2_session_test.h \
 	nghttp2_frame_test.h nghttp2_stream_test.h nghttp2_hd_test.h \
-	nghttp2_npn_test.h nghttp2_gzip_test.h nghttp2_helper_test.h \
+	nghttp2_npn_test.h nghttp2_helper_test.h \
 	nghttp2_test_helper.h \
 	nghttp2_buf_test.h