macports gcc4.7 can't find pthread.h

Question

I have installed gcc4.7 with macports and tryding to build Ogre3d 1.8.

The problem is that pthread.h is not found. I can't find pthread.h anywhere on my system (Mac OSX 10.6.8) and I can't find any ports on macports for pthread. Does anyone know if the gcc47 compiler from macports is broken? I downloaded the source for the gcc4.7 compiler and the zip file contained a pthread.h.

(as you can read in the log is the pthread.h included from a system header file and not Ogre3d, so I can't just skip the dependency)

The error output:

In file included from /opt/local/include/gcc47/c++//x86_64-apple-darwin10/bits/gthr.h:150:0,
                 from /opt/local/include/gcc47/c++/ext/atomicity.h:34,
                 from /opt/local/include/gcc47/c++/bits/basic_string.h:41,
                 from /opt/local/include/gcc47/c++/string:54,
                 from /Users/parwrange/Documents/Blacksun/src/blacksun/3rdPartySrc/ogre_src_v1-8-1/OgreMain/include/OgrePrerequisites.h:33,
                 from /Users/parwrange/Documents/Blacksun/src/blacksun/3rdPartySrc/ogre_src_v1-8-1/OgreMain/include/OgreArchive.h:31,
                 from /Users/parwrange/Documents/Blacksun/src/blacksun/3rdPartySrc/ogre_src_v1-8-1/OgreMain/include/OgreStableHeaders.h:41,
                 from /Users/parwrange/Documents/Blacksun/src/blacksun/3rdPartySrc/ogre_src_v1-8-1/OgreMain/src/OgreAlignedAllocator.cpp:28:
/opt/local/include/gcc47/c++//x86_64-apple-darwin10/bits/gthr-default.h:41:21: fatal error: pthread.h: No such file or directory