zehn_loader: Make sure padding ends up in the raw binary

The previous alignment instruction was a noop, as there was nothing past it.
Put alignment into a custom section and make sure it ends up in the binary.

ndless-sdk/tools/zehn_loader/Makefile

@@ -14,7 +14,7 @@ zehn_loader.tns.elf: loader.cpp
 	$(GXX) $(GXXFLAGS) $^ -o $@
 
 zehn_loade%.tns: zehn_loade%.tns.elf
-	$(OBJCOPY) -O binary $^ $@
+	$(OBJCOPY) --set-section-flags .pad=alloc,load,contents -O binary $^ $@
 
 zlib/Makefile: ../../thirdparty/zlib/configure
 	mkdir -p zlib

ndless-sdk/tools/zehn_loader/ldscript

@@ -11,7 +11,6 @@ SECTIONS
 		*(.got.plt);
 		*(.got);
 	}
-	/* .bss before .data, to make sure space is allocated for it in the binary file */
 	.bss : {
 		*(.bss);
 		*(.bss.*);
@@ -20,7 +19,10 @@ SECTIONS
 		*(.data);
 		*(.data.*);
 	}
-
-	. = ALIGN(4);
+	/* Put padding into its own section which is force included
+	   by the objcopy call. This ensures that NOBITS data is filled. */
+	.pad : {
+		. = ALIGN(4);
+	}
 }
 zehn_start = .;