These parameters are only used as bools. This also
renames "flag" to "relocatable" to make it clearer
what it does.

gdb/ChangeLog:

2019-09-06  Christian Biesinger  <cbiesinger@google.com>

	* defs.h (relocate_gdb_directory): Change int to bool in
	signature and rename flag to relocatable.
	* main.c (relocate_path): Likewise.
	(relocate_gdb_directory): Likewise.