[BUILD] add the USE_GETADDRINFO build option
This one is used to call getaddrinfo() to resolve IPv6 host names.
diff --git a/README b/README
index d16dadd..7834951 100644
--- a/README
+++ b/README
@@ -70,6 +70,17 @@
Warning! group references on Solaris seem broken. Use static-pcre whenever
possible.
+Recent systems can resolve IPv6 host names using getaddrinfo(). This primitive
+is not present in all libcs and does not work in all of them either. Support in
+glibc was broken before 2.3. Some embedded libs may not properly work either,
+thus, support is disabled by default, meaning that some host names which only
+resolve as IPv6 addresses will not resolve and configs might emit an error
+during parsing. If you know that your OS libc has reliable support for
+getaddrinfo(), you can add USE_GETADDRINFO=1 on the make command line to enable
+it. This is the recommended option for most Linux distro packagers since it's
+working fine on all recent mainstream distros. It is automatically enabled on
+Solaris 8 and above, as it's known to work.
+
By default, the DEBUG variable is set to '-g' to enable debug symbols. It is
not wise to disable it on uncommon systems, because it's often the only way to
get a complete core when you need one. Otherwise, you can set DEBUG to '-s' to