SF but #417587: compiler warnings compiling 2.1.

Repaired *some* of the SGI compiler warnings Sjoerd Mullender reported.

Modules/mmapmodule.c

@@ -818,7 +818,7 @@ new_mmap_object(PyObject *self, PyObject *args, PyObject *kwdict)
 	m_obj->data = mmap(NULL, map_size, 
 			   prot, flags,
 			   fd, 0);
-	if (m_obj->data == (void *)-1)
+	if (m_obj->data == (char *)-1)
 	{
 		Py_DECREF(m_obj);
 		PyErr_SetFromErrno(mmap_module_error);

Objects/unicodeobject.c

@@ -671,12 +671,10 @@ PyObject *PyUnicode_DecodeUTF8(const char *s,
         case 0:
             errmsg = "unexpected code byte";
 	    goto utf8Error;
-            break;
 
         case 1:
             errmsg = "internal error";
 	    goto utf8Error;
-            break;
 
         case 2:
             if ((s[1] & 0xc0) != 0x80) {
@@ -740,7 +738,6 @@ PyObject *PyUnicode_DecodeUTF8(const char *s,
             /* Other sizes are only needed for UCS-4 */
             errmsg = "unsupported Unicode code range";
 	    goto utf8Error;
-	    break;
         }
         s += n;
 	continue;

Parser/tokenizer.c

@@ -445,7 +445,6 @@ PyToken_ThreeChars(int c1, int c2, int c3)
 			switch (c3) {
 			case '=':
 				return LEFTSHIFTEQUAL;
-				break;
 			}
 			break;
 		}
@@ -456,7 +455,6 @@ PyToken_ThreeChars(int c1, int c2, int c3)
 			switch (c3) {
 			case '=':
 				return RIGHTSHIFTEQUAL;
-				break;
 			}
 			break;
 		}
@@ -467,7 +465,6 @@ PyToken_ThreeChars(int c1, int c2, int c3)
 			switch (c3) {
 			case '=':
 				return DOUBLESTAREQUAL;
-				break;
 			}
 			break;
 		}

Python/ceval.c

@@ -2146,7 +2146,6 @@ eval_code2(PyCodeObject *co, PyObject *globals, PyObject *locals,
 			opcode = NEXTOP();
 			oparg = oparg<<16 | NEXTARG();
 			goto dispatch_opcode;
-			break;
 
 		default:
 			fprintf(stderr,