sparc: support static_key usage in non-module __exit sections

The jump table can reference text found in an __exit section.  Thus,
instead of discarding it at build/link time, include EXIT_TEXT as part
of __init and release it at system boot time.

Without this patch the link fails with:

    `.exit.text' referenced in section `__jump_table' of xxx.o:
    defined in discarded section `.exit.text' of xxx.o

Link: http://lkml.kernel.org/r/d822da427ab07a02a394602eca687104ff682f83.1467837322.git.jbaron@akamai.comSigned-off-by: Jason Baron <jbaron@akamai.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Joe Perches <joe@perches.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/sparc/kernel/vmlinux.lds.S

@@ -150,6 +150,13 @@ SECTIONS
 	}
 	PERCPU_SECTION(SMP_CACHE_BYTES)
 
+#ifdef CONFIG_JUMP_LABEL
+	. = ALIGN(PAGE_SIZE);
+	.exit.text : {
+		EXIT_TEXT
+	}
+#endif
+
 	. = ALIGN(PAGE_SIZE);
 	__init_end = .;
 	BSS_SECTION(0, 0, 0)