Support systems with a lib64 site config.

Fixes #1562

CHANGELOG.md

@@ -23,6 +23,7 @@
 ## Bugs
 
 * HTML::SAX::Parser#parse_io now correctly parses HTML and not XML [#1577] (Thanks for the test case, @gregors!)
+* Support installation on systems with a `lib64` site config. [#1562]
 * [MRI] on OpenBSD, do not require gcc if using system libraries [#1515] (Thanks, @jeremyevans!)
 * [MRI] XML::Attr.new checks type of Document arg to prevent segfaults. [#1477]
 * [JRuby] correctly append a text node before another text node [#1318] (Thanks, @jkraemer!)

ext/nokogiri/extconf.rb

@@ -260,11 +260,12 @@ def chdir_for_build
 
 def process_recipe(name, version, static_p, cross_p)
   MiniPortile.new(name, version).tap do |recipe|
-    recipe.target = portsdir = File.join(ROOT, "ports")
+    recipe.target = File.join(ROOT, "ports")
     # Prefer host_alias over host in order to use i586-mingw32msvc as
     # correct compiler prefix for cross build, but use host if not set.
     recipe.host = RbConfig::CONFIG["host_alias"].empty? ? RbConfig::CONFIG["host"] : RbConfig::CONFIG["host_alias"]
     recipe.patch_files = Dir[File.join(ROOT, "patches", name, "*.patch")].sort
+    recipe.configure_options << "--libdir=#{File.join(recipe.path, "lib")}"
 
     yield recipe