x86, vdso: Actually discard the .discard sections

The .discard/.discard.* sections are used to generate intermediate
results for the assembler (effectively "test assembly".)  The output
is waste and should not be retained.

Cc: Stefani Seibold <stefani@seibold.net>
Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/n/tip-psizrnant8x3nrhbgvq2vekr@git.kernel.org

arch/x86/vdso/vdso-layout.lds.S

@@ -62,6 +62,11 @@ SECTIONS
 	. = ALIGN(0x100);
 
 	.text		: { *(.text*) }			:text	=0x90909090
+
+	/DISCARD/ : {
+		*(.discard)
+		*(.discard.*)
+	}
 }
 
 /*