fix compilation

golang/_golang.pyx

@@ -564,7 +564,7 @@ cdef extern from "golang/libgolang.h" namespace "golang" nogil:
 
     void _taskgo(void (*f)(void *), void *arg)
 
-cdef nogil:
+cdef extern nogil:
 
     _chan* _makechan_pyexc(unsigned elemsize, unsigned size)    except +topyexc:
         return _makechan(elemsize, size)
@@ -916,7 +916,7 @@ cdef class pyerror(Exception):
 
 # ---- misc ----
 
-cdef nogil:
+cdef extern nogil:
 
     error errors_New_pyexc(const char* text)            except +topyexc:
         return errors.New(text)