Inline convert_voidptr to tkagg.

It's only used in this file, and pulling in the whole `py_converters.h`
causes this extension to unnecessarily require compiling against NumPy.

Author: QuLogic

setupext.py

@@ -447,7 +447,6 @@ def get_extensions(self):
         ext = Extension(
             "matplotlib.backends._tkagg", [
                 "src/_tkagg.cpp",
-                "src/py_converters.cpp",
             ],
             include_dirs=["src"],
             # psapi library needed for finding Tcl/Tk at run time.

src/_tkagg.cpp

@@ -33,14 +33,17 @@
 #define dlsym GetProcAddress
 #else
 #include <dlfcn.h>
-// Suppress -Wunused-function on POSIX, but not on Windows where that would
-// lead to PY_ARRAY_UNIQUE_SYMBOL being an unresolved external.
-#define NO_IMPORT_ARRAY
 #endif
 
 // Include our own excerpts from the Tcl / Tk headers
 #include "_tkmini.h"
-#include "py_converters.h"
+
+static int convert_voidptr(PyObject *obj, void *p)
+{
+    void **val = (void **)p;
+    *val = PyLong_AsVoidPtr(obj);
+    return *val != NULL ? 1 : !PyErr_Occurred();
+}
 
 // Global vars for Tk functions.  We load these symbols from the tkinter
 // extension module or loaded Tk libraries at run-time.

src/py_converters.cpp

@@ -94,13 +94,6 @@ int convert_from_attr(PyObject *obj, const char *name, converter func, void *p)
     return 1;
 }
 
-int convert_voidptr(PyObject *obj, void *p)
-{
-    void **val = (void **)p;
-    *val = PyLong_AsVoidPtr(obj);
-    return *val != NULL ? 1 : !PyErr_Occurred();
-}
-
 int convert_double(PyObject *obj, void *p)
 {
     double *val = (double *)p;

src/py_converters.h

@@ -22,7 +22,6 @@ typedef int (*converter)(PyObject *, void *);
 int convert_from_attr(PyObject *obj, const char *name, converter func, void *p);
 int convert_from_method(PyObject *obj, const char *name, converter func, void *p);
 
-int convert_voidptr(PyObject *obj, void *p);
 int convert_double(PyObject *obj, void *p);
 int convert_bool(PyObject *obj, void *p);
 int convert_cap(PyObject *capobj, void *capp);