BUILD: makefile: Enable closefrom() support on Solaris

Solaris 9 (released 2002) added support for closefrom().

I bumped the version in the comment to 10 as the default feature
flags already has event ports enabled which were introduced in
Solaris 10.

INSTALL

@@ -374,7 +374,7 @@ and assign it to the TARGET variable :
   - linux-glibc         for Linux kernel 2.6.28 and above
   - linux-glibc-legacy  for Linux kernel 2.6.28 and above without new features
   - linux-musl          for Linux kernel 2.6.28 and above with musl libc
-  - solaris             for Solaris 8 or 10 (others untested)
+  - solaris             for Solaris 10 and above
   - freebsd             for FreeBSD 5 to 12 (others untested)
   - netbsd              for NetBSD
   - osx                 for Mac OS/X

Makefile

@@ -355,12 +355,11 @@ ifneq ($(shell echo __arm__/__aarch64__ | $(CC) -E -xc - | grep '^[^\#]'),__arm_
 endif
 endif
 
-# Solaris 8 and above
+# Solaris 10 and above
 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_RT USE_OBSOLETE_LINKER USE_EVPORTS)
+    USE_RT USE_OBSOLETE_LINKER USE_EVPORTS USE_CLOSEFROM)
   TARGET_CFLAGS  = -DFD_SETSIZE=65536 -D_REENTRANT -D_XOPEN_SOURCE=500 -D__EXTENSIONS__
   TARGET_LDFLAGS = -lnsl -lsocket
 endif