openssl - could not find the C header files

[Frank Röhm]

Hello 

one and half a year ago I compiled tor easily “tor” from the original source on my MacBook Pro (2009/11) with at this time still OS 10.6.8
No worries there.

Now I want to re-compile the new and actual tor-0.2.7.3-rc source under El Capitan (OS 10.11) but I get errors.

I had updated the Xcode to 7.1 Beta 3, installed the actual OS 10.11 command line tools and updated  macports (under big problems, because of the broken rsync server, so I had to download the svn repo and use it as source) and ran  "port upgrade outdated", which seems ok.

Now when I try to run “./configure” in the tor source dir, I get this error:
...
checking for openssl directory... configure: WARNING: We found the libraries for openssl, but we could not find the C header files.  You may need to install a devel package.
configure: error: Missing headers; unable to proceed.

openssl is installed:

MacBook:dports root# port list installed
...
openssl                        @1.0.2d         devel/openssl
…

but the compiler doesn’t find the header I guess.

openssl is in:

MacBook:tor-0.2.7.3-rc f$ which openssl
/opt/local/bin/openssl

this version:

MacBook:tor-0.2.7.3-rc f$ openssl version
OpenSSL 1.0.2d 9 Jul 2015

so now I don’t know how to get rid of this error. Could one help?
Thank's

frank