Make relocate_{path,gdb_directory} return std::string

This simplifies memory management. I've also changed some global variables
to std::string accordingly (which store the result of these functions),
but not all because some are used with add_setshow_optional_filename_cmd
which requires a char*.

gdb/ChangeLog:

2019-09-11  Christian Biesinger  <cbiesinger@google.com>

	* auto-load.c (auto_load_expand_dir_vars): Update.
	* defs.h (gdb_datadir): Change to std::string.
	(python_libdir): Likewise.
	(relocate_gdb_directory): Change return type to std::string.
	* guile/guile.c (gdbscm_data_directory): Update.
	(initialize_scheme_side): Update.
	* jit.c (jit_reader_dir): Change to std::string.
	(jit_reader_load_command): Update.
	* main.c (gdb_datadir): Change to std::string.
	(python_libdir): Likewise.
	(set_gdb_data_directory): Update.
	(relocate_path): Change to return std::string.
	(relocate_gdb_directory): Change to return std::string.
	(relocate_gdbinit_path_maybe_in_datadir): Update.
	(captured_main_1): Update.
	* python/python.c (do_start_initialization): Update.
	* top.c (show_gdb_datadir): Update.
	* xml-syscall.c (xml_init_syscalls_info): Update.
	(init_syscalls_info): Update.

1 files changed, 1 insertions, 1 deletions

diff --git a/gdb/top.c b/gdb/top.c
index 9d4ce1f..2b53640 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -2038,7 +2038,7 @@ show_gdb_datadir (struct ui_file *file, int from_tty,
 		  struct cmd_list_element *c, const char *value)
 {
   fprintf_filtered (file, _("GDB's data directory is \"%s\".\n"),
-		    gdb_datadir);
+		    gdb_datadir.c_str ());
 }
 
 static void