Add xfreopen.c to the library build, fixes DEBUG build.

The actual xfreopen function is only relevant if O_BINARY != 0 and all
places invoking it are surrounded by if statements that are always
false if O_BINARY == 0. The compiler therefore stripped all the calls
out at the default -O2, but this obviously breaks down with DEBUG on.

src/bin/coreutils/lib/Jamfile

@@ -223,6 +223,7 @@ StaticLibrary libfetish.a :
 	version-etc-fsf.c
 	write-any-file.c
 	xalloc-die.c
+	xfreopen.c
 	xfts.c
 	xgetcwd.c
 	xgethostname.c