title: check header file of iconv.h
body: <p>I am using FreeBSD and have installed <code>iconv</code> package form port collection.I wrote </p>
  
  <p><code>AC_CHECK_HEADER([iconv.h], ,[AC_MSG_ERROR([can not find iconv.h])])</code>
  <code>AC_CHECK_LIB([iconv], [iconv_open], ,[AC_MSG_ERROR([can not find iconv_open])])</code></p>
  
  <p>in the configure.ac.But when I run ./configure, it gave me the following message</p>
  
  <p><code>checking iconv.h usability... no</code></p>
  
  <p><code>checking iconv.h presence... no</code></p>
  
  <p><code>checking for iconv.h... no</code></p>
  
  <p><code>configure: error: can not find iconv.h</code></p>
  
  <p>I am sure there is <code>iconv.h</code>, <code>libiconv.la</code>, <code>libiconv.so</code> in the directory of <code>/usr/local/include</code> and <code>/usr/local/lib</code>.So how should I write the correct statement to check the header file and library.Thanks advance!!</p>