title: error installing WWW::Curl::Easy "Cannot build Constants" MacOS
body: <p>I'm trying to install the WWW::Curl::Easy module on MacOS10.12.4 and it fails stating "Cannot find curl.h - cannot build constants file".</p>
  
  <p>Curl-config in /usr/bin has an includedir of /usr/include, which does not exist.  I checked the Makefile with the perl module, and it lists several other locations it looks, such as /usr/local/include, /usr/local, etc.  Those didn't exist, but I made them and copied the curl.h that comes with XCode into them.</p>
  
  <p>I still receive the same error.  Here is the log:</p>
  
  <pre><code>cpanm (App::cpanminus) 1.7043 on perl 5.016000 built for darwin-2level
  Work directory is /Users/thisUser/.cpanm/work/1493902651.14410
  You have make /usr/bin/make
  You have /usr/bin/curl
  You have /usr/bin/tar: bsdtar 2.8.3 - libarchive 2.8.3
  You have /usr/bin/unzip
  Searching WWW::Curl::Easy () on cpanmetadb ...
  --&gt; Working on WWW::Curl::Easy
  Fetching http://www.cpan.org/authors/id/S/SZ/SZBALINT/WWW-Curl-4.17.tar.gz
  -&gt; OK
  Unpacking WWW-Curl-4.17.tar.gz
  Entering WWW-Curl-4.17
  Checking configure dependencies from META.yml
  Checking if you have ExtUtils::MakeMaker 6.58 ... Yes (6.63_02)
  Configuring WWW-Curl-4.17
  Running Makefile.PL
  Locating required external dependency bin:curl-config... found at /usr/bin/curl-config.
  The version is libcurl 7.51.0
  Cannot find curl.h - cannot build constants files  - see Makefile.PL at Makefile.PL line 96.
  -&gt; N/A
  -&gt; FAIL Configure failed for WWW-Curl-4.17. See /Users/thisUser/.cpanm/work/1493902651.14410/build.log for details.
  </code></pre>
  
  <p>I've done my best searches here and on Google, and not finding an answer. I didn't have this issue when I installed this on my last Mac, so not sure what was changed.</p>