tracing/function-graph-tracer: add a new .irqentry.text section, fix

Impact: build fix

32-bit x86 needs this section too.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/vmlinux_32.lds.S

@@ -44,6 +44,7 @@ SECTIONS
 	SCHED_TEXT
 	LOCK_TEXT
 	KPROBES_TEXT
+	IRQENTRY_TEXT
 	*(.fixup)
 	*(.gnu.warning)
   	_etext = .;			/* End of text section */