Improve SyntaxErrors for bad future statements.  Set file and location
for errors raised in future.c.

Move some helper functions from compile.c to errors.c and make them
API functions: PyErr_SyntaxLocation() and PyErr_ProgramText().
diff --git a/Include/pyerrors.h b/Include/pyerrors.h
index c8c3d82..7d8ed84 100644
--- a/Include/pyerrors.h
+++ b/Include/pyerrors.h
@@ -98,6 +98,10 @@
 /* In sigcheck.c or signalmodule.c */
 extern DL_IMPORT(int) PyErr_CheckSignals(void);
 extern DL_IMPORT(void) PyErr_SetInterrupt(void);
+
+/* Support for adding program text to SyntaxErrors */
+extern DL_IMPORT(void) PyErr_SyntaxLocation(char *, int);
+extern DL_IMPORT(PyObject *) PyErr_ProgramText(char *, int);
 	
 
 #ifdef __cplusplus