add some backcompat in nc, don't install it

apps/nc/Makefile.am

@@ -1,6 +1,8 @@
 include $(top_srcdir)/Makefile.am.common
 
-bin_PROGRAMS = nc
+if HAVE_POLL
+
+noinst_PROGRAMS = nc
 
 nc_LDADD = $(PLATFORM_LDADD) $(PROG_LDADD)
 nc_LDADD += $(top_builddir)/tls/libtls.la
@@ -9,3 +11,9 @@ nc_SOURCES = atomicio.c
 nc_SOURCES += netcat.c
 nc_SOURCES += socks.c
 noinst_HEADERS = atomicio.h
+
+if !HAVE_STRTONUM
+nc_SOURCES += compat/strtonum.c
+endif
+
+endif