Refactor: Keep information about OpenLDAP constants in Python, genera…

…te C

Modules/errors.{c,h} are merged into Modules/constants.{c,h}

The function LDAPerror_TypeError is moved to common.{c,h}, as it's not
concerned with LDAPError.

Add a new Python module, ldap.constants, to keep information about
all OpenLDAP constants that we know about, including those that aren't
available in the OpenLDAP used.

Generate a C header file, Modules/constants_generated.h, from this information.
(Checking generated files into Git is better avoided, but it's much
more straightforward than generating the file from setup.py.)

Use proper error checking when adding the constants.

Modules/LDAPObject.c

@@ -5,7 +5,6 @@
 
 #include <math.h>
 #include <limits.h>
-#include "errors.h"
 #include "constants.h"
 #include "LDAPObject.h"
 #include "ldapcontrol.h"

Modules/common.c

@@ -16,3 +16,15 @@ LDAPadd_methods( PyObject* d, PyMethodDef* methods )
         Py_DECREF(f);
     }
 }
+
+/* Raise TypeError with custom message and object */
+PyObject*
+LDAPerror_TypeError(const char *msg, PyObject *obj) {
+    PyObject *args = Py_BuildValue("sO", msg, obj);
+    if (args == NULL) {
+        return NULL;
+    }
+    PyErr_SetObject(PyExc_TypeError, args);
+    Py_DECREF(args);
+    return NULL;
+}

Modules/common.h

@@ -24,6 +24,8 @@
 #define streq( a, b ) \
 	( (*(a)==*(b)) && 0==strcmp(a,b) )
 
+extern PyObject* LDAPerror_TypeError(const char *, PyObject *);
+
 void LDAPadd_methods( PyObject*d, PyMethodDef*methods );
 #define PyNone_Check(o) ((o) == Py_None)