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, 2 insertions, 2 deletions

diff --git a/gdb/jit.c b/gdb/jit.c
index 5fef037..4722d6c 100644
--- a/gdb/jit.c
+++ b/gdb/jit.c
@@ -42,7 +42,7 @@
 #include "readline/tilde.h"
 #include "completer.h"
 
-static const char *jit_reader_dir = NULL;
+static std::string jit_reader_dir;
 
 static const struct objfile_data *jit_objfile_data;
 
@@ -216,7 +216,7 @@ jit_reader_load_command (const char *args, int from_tty)
     error (_("JIT reader already loaded.  Run jit-reader-unload first."));
 
   if (!IS_ABSOLUTE_PATH (file.get ()))
-    file.reset (xstrprintf ("%s%s%s", jit_reader_dir, SLASH_STRING,
+    file.reset (xstrprintf ("%s%s%s", jit_reader_dir.c_str (), SLASH_STRING,
 			    file.get ()));
 
   loaded_jit_reader = jit_reader_load (file.get ());