libpayload; put the ldscript into an arch-dependent directory path

Since it's utterly architecture-dependent, put it in arch/x86.
Avoid the temptation to make yet another directory with just one
file in it. Fix the makefile to pick up the proper arch-dependent script.

Change-Id: I21ea02551a97bdcbc38419714f3b38cf8335c178
Signed-off-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-on: http://review.coreboot.org/2389
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>

payloads/libpayload/Makefile.inc

@@ -97,7 +97,7 @@ install: real-target
 	for lib in $(library-targets); do \
 		install -m 644 $$lib $(DESTDIR)/libpayload/lib/; \
 	done
-	install -m 644 lib/libpayload.ldscript $(DESTDIR)/libpayload/lib/
+	install -m 644 arch/$(ARCHDIR-y)/libpayload.ldscript $(DESTDIR)/libpayload/lib/
 	install -m 755 -d $(DESTDIR)/libpayload/lib/$(ARCHDIR-y)
 	install -m 644 $(obj)/head.o $(DESTDIR)/libpayload/lib/$(ARCHDIR-y)
 	printf "    INSTALL    $(DESTDIR)/libpayload/include\n"