mkconfig.rb: cross_compiling option

* common.mk, tool/mkconfig.rb: set cross_compiling option from
  Makefile, but not from rbconfig.rb, which is just going to be
  created by this command.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53969 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Mon Feb 29 16:31:01 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* common.mk, tool/mkconfig.rb: set cross_compiling option from
+	  Makefile, but not from rbconfig.rb, which is just going to be
+	  created by this command.
+
 Sun Feb 28 23:13:49 2016  C.J. Collier  <cjcollier@linuxfoundation.org>
 
 	* configure.in: Add summary to end of configure output.

common.mk

@@ -625,6 +625,7 @@ extconf: $(PREP)
 
 $(RBCONFIG): $(srcdir)/tool/mkconfig.rb config.status $(srcdir)/version.h
 	$(Q)$(BOOTSTRAPRUBY) $(srcdir)/tool/mkconfig.rb -timestamp=$@ \
+		-cross_compiling=$(CROSS_COMPILING) \
 		-arch=$(arch) -version=$(RUBY_PROGRAM_VERSION) \
 		-install_name=$(RUBY_INSTALL_NAME) \
 		-so_name=$(RUBY_SO_NAME) rbconfig.rb

tool/mkconfig.rb

@@ -8,11 +8,12 @@
 # avoid warnings with -d.
 $install_name ||= nil
 $so_name ||= nil
+$cross_compiling ||= nil
 arch = $arch or raise "missing -arch"
 version = $version or raise "missing -version"
 
 srcdir = File.expand_path('../..', __FILE__)
-$:.replace [srcdir+"/lib"] unless defined?(CROSS_COMPILING)
+$:.replace [srcdir+"/lib"] unless $cross_compiling == "yes"
 $:.unshift(".")
 
 require "fileutils"