patch the distutils to add the C source directory in the include path.

This should solve most of the compilation problems related to .h files
located in this directory

distutils.ext/obidistutils/core.py

@@ -40,6 +40,7 @@ def findPackage(root,base=None):
     
 def findCython(root,base=None,pyrexs=None):
     setupdir = os.path.dirname(sys.argv[0])
+    csourcedir = os.path.join(setupdir,"src")
     pyrexs=[]
 
     if base is None:
@@ -53,6 +54,7 @@ def findCython(root,base=None,pyrexs=None):
                                     [pyrex]
                                     )
                           )
+            pyrexs[-1].include_dirs.append(csourcedir)
             try:
                 cfiles = os.path.splitext(pyrex)[0]+".cfiles"
                 cfilesdir = os.path.dirname(cfiles)