[build] add $(ATTR_LIB) to liblightcomp_la_LIBADD

(for cygwin)

src/Makefile.am

@@ -98,7 +98,7 @@ lib_LTLIBRARIES += liblightcomp.la
 liblightcomp_la_SOURCES=$(common_src)
 liblightcomp_la_CFLAGS=$(AM_CFLAGS) $(LIBEV_CFLAGS)
 liblightcomp_la_LDFLAGS = $(common_ldflags)
-liblightcomp_la_LIBADD = $(PCRE_LIB) $(SSL_LIB) $(FAM_LIBS) $(LIBEV_LIBS)
+liblightcomp_la_LIBADD = $(PCRE_LIB) $(SSL_LIB) $(FAM_LIBS) $(LIBEV_LIBS) $(ATTR_LIB)
 common_libadd = liblightcomp.la
 else
 src += $(common_src)