unable to find objc.h during clang compile
===

I'm on Ubuntu 12.

I'm trying to compile an Objective-C hello_world app using clang. This is the source:

    #import <Foundation/Foundation.h>
    int main (int argc, const char * argv[])
    {
     NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
     NSLog (@"hello world");
     [pool drain];
     return 0;
    }


I use this commandline:

    . /usr/share/GNUstep/Makefiles/GNUstep.sh
    clang h.m `gnustep-config --objc-flags` -lgnustep-base -o hello

I get the following error:

    clang: warning: argument unused during compilation: '--param ssp-buffer-size=4'
    In file included from h.m:1:
    In file included from /usr/include/GNUstep/Foundation/Foundation.h:30:
    In file included from /usr/include/GNUstep/GNUstepBase/GSVersionMacros.h:193:
    In file included from /usr/include/GNUstep/GNUstepBase/GSConfig.h:229:
    /usr/include/GNUstep/GNUstepBase/preface.h:112:11: fatal error: 'objc/objc.h'
          file not found
     #include <objc/objc.h>
              ^
    1 error generated.

The same commandline using gcc works fine. 

Any ideas how to fix this missing objc.h error?
