Try to fix a bunch of compiler warnings on Win64.

Objects/unicodeobject.c

@@ -7261,7 +7261,7 @@ unicode_repeat(PyUnicodeObject *str, Py_ssize_t len)
             done = str->length;
 	}
 	while (done < nchars) {
-            int n = (done <= nchars-done) ? done : nchars-done;
+            Py_ssize_t n = (done <= nchars-done) ? done : nchars-done;
             Py_UNICODE_COPY(p+done, p, n);
             done += n;
 	}

PC/_winreg.c

@@ -715,7 +715,7 @@ countStrings(char *data, int len)
 static BOOL
 Py2Reg(PyObject *value, DWORD typ, BYTE **retDataBuf, DWORD *retDataSize)
 {
-	int i,j;
+	Py_ssize_t i,j;
 	switch (typ) {
 		case REG_DWORD:
 			if (value != Py_None && !PyInt_Check(value))

PC/w9xpopen.c

@@ -30,7 +30,7 @@ int main(int argc, char *argv[])
     STARTUPINFO si;
     PROCESS_INFORMATION pi;
     DWORD exit_code=0;
-    int cmdlen = 0;
+    size_t cmdlen = 0;
     int i;
     char *cmdline, *cmdlinefill;
 

Python/peephole.c

@@ -29,7 +29,7 @@
    Also works for BUILD_LIST when followed by an "in" or "not in" test.
 */
 static int
-tuple_of_constants(unsigned char *codestr, int n, PyObject *consts)
+tuple_of_constants(unsigned char *codestr, Py_ssize_t n, PyObject *consts)
 {
 	PyObject *newconst, *constant;
 	Py_ssize_t i, arg, len_consts;
@@ -228,7 +228,7 @@ fold_unaryops_on_constants(unsigned char *codestr, PyObject *consts)
 }
 
 static unsigned int *
-markblocks(unsigned char *code, int len)
+markblocks(unsigned char *code, Py_ssize_t len)
 {
 	unsigned int *blocks = (unsigned int *)PyMem_Malloc(len*sizeof(int));
 	int i,j, opcode, blockcnt = 0;