lib/mkmf.rb: check pkg-config result

* lib/mkmf.rb (MakeMakefile#pkg_config): check if libs resulted from
  pkg-config works actually.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@35605 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Wed May  9 16:36:01 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/mkmf.rb (MakeMakefile#pkg_config): check if libs resulted from
+	  pkg-config works actually.
+
 Wed May  9 16:01:38 2012  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* lib/net/imap.rb (decode_utf7, encode_utf7): refactored by

lib/mkmf.rb

@@ -1655,9 +1655,8 @@ SRC
       # default to package specific config command, as a last resort.
       get = proc {|opt| `#{pkgconfig} --#{opt}`.chomp}
     end
-    if get
+    if get and try_ldflags(ldflags = get['libs'])
       cflags = get['cflags']
-      ldflags = get['libs']
       libs = get['libs-only-l']
       ldflags = (Shellwords.shellwords(ldflags) - Shellwords.shellwords(libs)).quote.join(" ")
       $CFLAGS += " " << cflags