bpo-40939: Rename PyPegen* functions to PyParser* (GH-21016)

Rename PyPegen* functions to PyParser*, so that we can remove the
old set of PyParser* functions that were using the old parser.

diff --git a/Include/Python.h b/Include/Python.h
index dcd0a57..57f71d4 100644
--- a/Include/Python.h
+++ b/Include/Python.h
@@ -141,6 +141,7 @@
 #include "modsupport.h"
 #include "compile.h"
 #include "pythonrun.h"
+#include "parser_interface.h"
 #include "pylifecycle.h"
 #include "ceval.h"
 #include "sysmodule.h"
diff --git a/Include/internal/pegen_interface.h b/Include/internal/pegen_interface.h
deleted file mode 100644
index ee4c77e..0000000
--- a/Include/internal/pegen_interface.h
+++ /dev/null
@@ -1,46 +0,0 @@
-#ifndef Py_PEGENINTERFACE
-#define Py_PEGENINTERFACE
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#ifndef Py_BUILD_CORE
-#  error "this header requires Py_BUILD_CORE define"
-#endif
-
-#include "Python.h"
-#include "Python-ast.h"
-
-PyAPI_FUNC(mod_ty) PyPegen_ASTFromString(
-    const char *str,
-    const char *filename,
-    int mode,
-    PyCompilerFlags *flags,
-    PyArena *arena);
-PyAPI_FUNC(mod_ty) PyPegen_ASTFromStringObject(
-    const char *str,
-    PyObject* filename,
-    int mode,
-    PyCompilerFlags *flags,
-    PyArena *arena);
-PyAPI_FUNC(mod_ty) PyPegen_ASTFromFileObject(
-    FILE *fp,
-    PyObject *filename_ob,
-    int mode,
-    const char *enc,
-    const char *ps1,
-    const char *ps2,
-    PyCompilerFlags *flags,
-    int *errcode,
-    PyArena *arena);
-PyAPI_FUNC(mod_ty) PyPegen_ASTFromFilename(
-    const char *filename,
-    int mode,
-    PyCompilerFlags *flags,
-    PyArena *arena);
-
-
-#ifdef __cplusplus
-}
-#endif
-#endif /* !Py_PEGENINTERFACE*/
diff --git a/Include/parser_interface.h b/Include/parser_interface.h
new file mode 100644
index 0000000..1c6576d
--- /dev/null
+++ b/Include/parser_interface.h
@@ -0,0 +1,52 @@
+#ifndef Py_PEGENINTERFACE
+#define Py_PEGENINTERFACE
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "Python.h"
+
+#ifndef Py_LIMITED_API
+PyAPI_FUNC(struct _mod *) PyParser_ASTFromString(
+    const char *str,
+    const char *filename,
+    int mode,
+    PyCompilerFlags *flags,
+    PyArena *arena);
+PyAPI_FUNC(struct _mod *) PyParser_ASTFromStringObject(
+    const char *str,
+    PyObject* filename,
+    int mode,
+    PyCompilerFlags *flags,
+    PyArena *arena);
+PyAPI_FUNC(struct _mod *) PyParser_ASTFromFile(
+    FILE *fp,
+    const char *filename,
+    const char* enc,
+    int mode,
+    const char *ps1,
+    const char *ps2,
+    PyCompilerFlags *flags,
+    int *errcode,
+    PyArena *arena);
+PyAPI_FUNC(struct _mod *) PyParser_ASTFromFileObject(
+    FILE *fp,
+    PyObject *filename_ob,
+    const char *enc,
+    int mode,
+    const char *ps1,
+    const char *ps2,
+    PyCompilerFlags *flags,
+    int *errcode,
+    PyArena *arena);
+PyAPI_FUNC(struct _mod *) PyParser_ASTFromFilename(
+    const char *filename,
+    int mode,
+    PyCompilerFlags *flags,
+    PyArena *arena);
+#endif /* !Py_LIMITED_API */
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_PEGENINTERFACE */
diff --git a/Include/pythonrun.h b/Include/pythonrun.h
index 46091e0..d43734b 100644
--- a/Include/pythonrun.h
+++ b/Include/pythonrun.h
@@ -32,57 +32,7 @@
     const char *filename,       /* decoded from the filesystem encoding */
     PyCompilerFlags *flags);
 
-PyAPI_FUNC(struct _mod *) PyParser_ASTFromString(
-    const char *s,
-    const char *filename,       /* decoded from the filesystem encoding */
-    int start,
-    PyCompilerFlags *flags,
-    PyArena *arena);
-PyAPI_FUNC(struct _mod *) PyParser_ASTFromStringObject(
-    const char *s,
-    PyObject *filename,
-    int start,
-    PyCompilerFlags *flags,
-    PyArena *arena);
-PyAPI_FUNC(struct _mod *) PyParser_ASTFromFile(
-    FILE *fp,
-    const char *filename,       /* decoded from the filesystem encoding */
-    const char* enc,
-    int start,
-    const char *ps1,
-    const char *ps2,
-    PyCompilerFlags *flags,
-    int *errcode,
-    PyArena *arena);
-PyAPI_FUNC(struct _mod *) PyParser_ASTFromFileObject(
-    FILE *fp,
-    PyObject *filename,
-    const char* enc,
-    int start,
-    const char *ps1,
-    const char *ps2,
-    PyCompilerFlags *flags,
-    int *errcode,
-    PyArena *arena);
-#endif
 
-#ifndef PyParser_SimpleParseString
-#define PyParser_SimpleParseString(S, B) \
-    PyParser_SimpleParseStringFlags(S, B, 0)
-#define PyParser_SimpleParseFile(FP, S, B) \
-    PyParser_SimpleParseFileFlags(FP, S, B, 0)
-#endif
-PyAPI_FUNC(struct _node *) PyParser_SimpleParseStringFlags(const char *, int,
-                                                           int);
-#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03030000
-PyAPI_FUNC(struct _node *) PyParser_SimpleParseStringFlagsFilename(const char *,
-                                                                   const char *,
-                                                                   int, int);
-#endif
-PyAPI_FUNC(struct _node *) PyParser_SimpleParseFileFlags(FILE *, const char *,
-                                                         int, int);
-
-#ifndef Py_LIMITED_API
 PyAPI_FUNC(PyObject *) PyRun_StringFlags(const char *, int, PyObject *,
                                          PyObject *, PyCompilerFlags *);