Use struct type rather than its name in conversion utility code.

This fixes #1739.

Cython/Compiler/PyrexTypes.py

@@ -3204,7 +3204,7 @@ class CStructOrUnionType(CType):
                     return False
 
             context = dict(
-                struct_name=self.name,
+                struct_type=self,
                 var_entries=self.scope.var_entries,
                 funcname=self.from_py_function,
             )

Cython/Utility/CConvert.pyx

@@ -8,8 +8,8 @@ cdef extern from *:
     object PyErr_Format(exc, const char *format, ...)
 
 @cname("{{funcname}}")
-cdef {{struct_name}} {{funcname}}(obj) except *:
-    cdef {{struct_name}} result
+cdef {{struct_type}} {{funcname}}(obj) except *:
+    cdef {{struct_type}} result
     if not PyMapping_Check(obj):
         PyErr_Format(TypeError, b"Expected %.16s, got %.200s", b"a mapping", Py_TYPE(obj).tp_name)
 
@@ -33,8 +33,8 @@ cdef extern from *:
     object PyErr_Format(exc, const char *format, ...)
 
 @cname("{{funcname}}")
-cdef {{struct_name}} {{funcname}}(obj) except *:
-    cdef {{struct_name}} result
+cdef {{struct_type}} {{funcname}}(obj) except *:
+    cdef {{struct_type}} result
     cdef Py_ssize_t length
     if not PyMapping_Check(obj):
         PyErr_Format(TypeError, b"Expected %.16s, got %.200s", b"a mapping", Py_TYPE(obj).tp_name)