Remove outdated pystrings.swg

Remove pystring.swg - a very ancient copy from SWIG which does not
compile when using swig-4.2.0. Instead SWIG's version of pystrings.swg
that is kept up to date in SWIG is used. SWIG_PYTHON_STRICT_BYTE_CHAR
needs to be defined in order to maintain the current behaviour of only
allowing Python 3 byte type instead of Python 3 string type as input.

As the output of swig is in graphviz_wrap.c and is committed to the
repo, the updates committed in this file (keeping the current swig-4.1.1
version). A later commit could update it to swig-4.2.0.

Fixes build problems on Fedora where SWIG_Python_str_AsChar no longer exists,
as reported at swig/swig#2778.

pygraphviz/graphviz.i

@@ -1,5 +1,9 @@
 %module graphviz
 
+%begin %{
+#define SWIG_PYTHON_STRICT_BYTE_CHAR
+%}
+
 %{
 #include "graphviz/cgraph.h"
 #include "graphviz/gvc.h"

pygraphviz/graphviz_wrap.c

@@ -6,6 +6,9 @@
  * the SWIG interface file instead.
  * ----------------------------------------------------------------------------- */
 
+#define SWIG_PYTHON_STRICT_BYTE_CHAR
+
+
 
 #define SWIG_VERSION 0x040101
 #define SWIGPYTHON
@@ -3038,49 +3041,96 @@ SWIGINTERN int
 SWIG_AsCharPtrAndSize(PyObject *obj, char** cptr, size_t* psize, int *alloc)
 {
 #if PY_VERSION_HEX>=0x03000000
+#if defined(SWIG_PYTHON_STRICT_BYTE_CHAR)
   if (PyBytes_Check(obj))
 #else
+  if (PyUnicode_Check(obj))
+#endif
+#else  
   if (PyString_Check(obj))
 #endif
   {
     char *cstr; Py_ssize_t len;
+    int ret = SWIG_OK;
 #if PY_VERSION_HEX>=0x03000000
-    PyBytes_AsStringAndSize(obj, &cstr, &len);
-    if(alloc) *alloc = SWIG_NEWOBJ;
+#if !defined(SWIG_PYTHON_STRICT_BYTE_CHAR)
+    if (!alloc && cptr) {
+        /* We can't allow converting without allocation, since the internal
+           representation of string in Python 3 is UCS-2/UCS-4 but we require
+           a UTF-8 representation.
+           TODO(bhy) More detailed explanation */
+        return SWIG_RuntimeError;
+    }
+    obj = PyUnicode_AsUTF8String(obj);
+    if (!obj)
+      return SWIG_TypeError;
+    if (alloc)
+      *alloc = SWIG_NEWOBJ;
+#endif
+    if (PyBytes_AsStringAndSize(obj, &cstr, &len) == -1)
+      return SWIG_TypeError;
 #else
-    PyString_AsStringAndSize(obj, &cstr, &len);
+    if (PyString_AsStringAndSize(obj, &cstr, &len) == -1)
+      return SWIG_TypeError;
 #endif
     if (cptr) {
       if (alloc) {
-	/*
-	   In python the user should not be able to modify the inner
-	   string representation. To warranty that, if you define
-	   SWIG_PYTHON_SAFE_CSTRINGS, a new/copy of the python string
-	   buffer is always returned.
-
-	   The default behavior is just to return the pointer value,
-	   so, be careful.
-	*/
-#if defined(SWIG_PYTHON_SAFE_CSTRINGS)
-	if (*alloc != SWIG_OLDOBJ)
-#else
-	if (*alloc == SWIG_NEWOBJ)
-#endif
-	  {
-	    *cptr = (char *)memcpy(malloc((len + 1)*sizeof(char)), cstr, sizeof(char)*(len + 1));
-	    *alloc = SWIG_NEWOBJ;
-	  }
-	else {
+	if (*alloc == SWIG_NEWOBJ) {
+	  *cptr = (char *)memcpy(malloc((len + 1)*sizeof(char)), cstr, sizeof(char)*(len + 1));
+	  *alloc = SWIG_NEWOBJ;
+	} else {
 	  *cptr = cstr;
 	  *alloc = SWIG_OLDOBJ;
 	}
       } else {
+#if PY_VERSION_HEX>=0x03000000
+#if defined(SWIG_PYTHON_STRICT_BYTE_CHAR)
+	*cptr = PyBytes_AsString(obj);
+#else
+	assert(0); /* Should never reach here with Unicode strings in Python 3 */
+#endif
+#else
 	*cptr = SWIG_Python_str_AsChar(obj);
+        if (!*cptr)
+          ret = SWIG_TypeError;
+#endif
       }
     }
     if (psize) *psize = len + 1;
-    return SWIG_OK;
+#if PY_VERSION_HEX>=0x03000000 && !defined(SWIG_PYTHON_STRICT_BYTE_CHAR)
+    Py_XDECREF(obj);
+#endif
+    return ret;
   } else {
+#if defined(SWIG_PYTHON_2_UNICODE)
+#if defined(SWIG_PYTHON_STRICT_BYTE_CHAR)
+#error "Cannot use both SWIG_PYTHON_2_UNICODE and SWIG_PYTHON_STRICT_BYTE_CHAR at once"
+#endif
+#if PY_VERSION_HEX<0x03000000
+    if (PyUnicode_Check(obj)) {
+      char *cstr; Py_ssize_t len;
+      if (!alloc && cptr) {
+        return SWIG_RuntimeError;
+      }
+      obj = PyUnicode_AsUTF8String(obj);
+      if (!obj)
+        return SWIG_TypeError;
+      if (PyString_AsStringAndSize(obj, &cstr, &len) != -1) {
+        if (cptr) {
+          if (alloc) *alloc = SWIG_NEWOBJ;
+          *cptr = (char *)memcpy(malloc((len + 1)*sizeof(char)), cstr, sizeof(char)*(len + 1));
+        }
+        if (psize) *psize = len + 1;
+
+        Py_XDECREF(obj);
+        return SWIG_OK;
+      } else {
+        Py_XDECREF(obj);
+      }
+    }
+#endif
+#endif
+
     swig_type_info* pchar_descriptor = SWIG_pchar_descriptor();
     if (pchar_descriptor) {
       void* vptr = 0;
@@ -3311,13 +3361,17 @@ SWIG_FromCharPtrAndSize(const char* carray, size_t size)
   if (carray) {
     if (size > INT_MAX) {
       swig_type_info* pchar_descriptor = SWIG_pchar_descriptor();
-      return pchar_descriptor ?
+      return pchar_descriptor ? 
 	SWIG_InternalNewPointerObj((char *)(carray), pchar_descriptor, 0) : SWIG_Py_Void();
     } else {
 #if PY_VERSION_HEX >= 0x03000000
-      return PyBytes_FromStringAndSize(carray, (int)(size));
+#if defined(SWIG_PYTHON_STRICT_BYTE_CHAR)
+      return PyBytes_FromStringAndSize(carray, (Py_ssize_t)(size));
+#else
+      return PyUnicode_DecodeUTF8(carray, (Py_ssize_t)(size), "surrogateescape");
+#endif
 #else
-      return PyString_FromStringAndSize(carray, (int)(size));
+      return PyString_FromStringAndSize(carray, (Py_ssize_t)(size));
 #endif
     }
   } else {