Use gdb::unique_xmalloc_ptr when calling tilde_expand

Use gdb::unique_xmalloc_ptr when calling tilde_expand

This patch changes most sites calling tilde_expand to use
gdb::unique_xmalloc_ptr, rather than a cleanup.  It also changes
scan_expression_with_cleanup to return a unique pointer, because the
patch was already touching code in that area.

Regression tested on the buildbot.

ChangeLog
2017-08-05  Tom Tromey  <tom@tromey.com>

	* compile/compile-object-load.c (compile_object_load): Use
	gdb::unique_xmalloc_ptr.
	* cli/cli-dump.c (scan_filename): Rename from
	scan_filename_with_cleanup.  Change return type.
	(scan_expression): Rename from scan_expression_with_cleanup.
	Change return type.
	(dump_memory_to_file, dump_value_to_file, restore_command):
	Use gdb::unique_xmalloc_ptr.  Update.
	* cli/cli-cmds.c (find_and_open_script): Use
	gdb::unique_xmalloc_ptr.
	* tracefile-tfile.c (tfile_open): Use gdb::unique_xmalloc_ptr.
	* symmisc.c (maintenance_print_symbols)
	(maintenance_print_msymbols): Use gdb::unique_xmalloc_ptr.
	* symfile.c (symfile_bfd_open, generic_load)
	(add_symbol_file_command, remove_symbol_file_command): Use
	gdb::unique_xmalloc_ptr.
	* source.c (openp): Use gdb::unique_xmalloc_ptr.
	* psymtab.c (maintenance_print_psymbols): Use
	gdb::unique_xmalloc_ptr.
	* corelow.c (core_open): Use gdb::unique_xmalloc_ptr.
	* breakpoint.c (save_breakpoints): Use gdb::unique_xmalloc_ptr.
	* solib.c (solib_map_sections): Use gdb::unique_xmalloc_ptr.
	(reload_shared_libraries_1): Likewise.