make gdbhooks.py idempotent with respect to reloading

gcc/ChangeLog:

2019-07-23  Vladislav Ivanishin <vlad@ispras.ru>

	* gdbhooks.py: Pass replace=True to
	gdb.printing.register_pretty_printer.

From-SVN: r273737

gcc/ChangeLog

+2019-07-23  Vladislav Ivanishin <vlad@ispras.ru>
+
+	* gdbhooks.py: Pass replace=True to
+	gdb.printing.register_pretty_printer.
+
 2019-07-23  Richard Biener  <rguenther@suse.de>
 
 	PR debug/91231

gcc/gdbhooks.py

@@ -605,7 +605,8 @@ def build_pretty_printer():
 
 gdb.printing.register_pretty_printer(
     gdb.current_objfile(),
-    build_pretty_printer())
+    build_pretty_printer(),
+    replace=True)
 
 def find_gcc_source_dir():
     # Use location of global "g" to locate the source tree