ld: Use stat to check if linker script appears multiple times

ld: Use stat to check if linker script appears multiple times

Use stat, instead of strcmp, to check if the same linker script file
appears multiple times for

$ ld -L... -T ././/script.t -T script.t ...

Although ././/script.t and script.t access the same file, but their
filenames are different.  strcmp won't work here.

Copy gnulib/import/same-inode.h to include since the gnulib directory
isn't included in the binutils tarball.

include/

	PR ld/24576
	* same-inode.h: New file.  Copied from gnulib/import/same-inode.h.

ld/

	PR ld/24576
	* ldfile.c: Include "same-inode.h".
	(ldfile_find_command_file): Change the second argument from bool
	to enum script_open_style.  Check if the same linker script file
	appears multiple times by using stat, instead using strcmp.
	(ldfile_open_command_file_1): Don't check if the same linker
	script file appears multiple times here.
	* testsuite/ld-scripts/pr24576-1.d: Adjusted.
	* testsuite/ld-scripts/pr24576-2.d: New.
	* testsuite/ld-scripts/script.exp: Run pr24576-2.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>