BUILD: makefile: use USE_OBSOLETE_LINKER for solaris

USE_OBSOLETE_LINKER is needed to build on SunOS systems.

This patch must be backported to 1.9.
diff --git a/Makefile b/Makefile
index 3248819..04451cd 100644
--- a/Makefile
+++ b/Makefile
@@ -351,7 +351,8 @@
 ifeq ($(TARGET),solaris)
   # We also enable getaddrinfo() which works since solaris 8.
   set_target_defaults = $(call default_opts, \
-    USE_POLL USE_TPROXY USE_LIBCRYPT USE_CRYPT_H USE_GETADDRINFO USE_THREAD)
+    USE_POLL USE_TPROXY USE_LIBCRYPT USE_CRYPT_H USE_GETADDRINFO USE_THREAD \
+    USE_OBSOLETE_LINKER)
   TARGET_CFLAGS  = -fomit-frame-pointer -DFD_SETSIZE=65536 -D_REENTRANT -D_XOPEN_SOURCE=500 -D__EXTENSIONS__
   TARGET_LDFLAGS = -lnsl -lsocket
 endif