kernel/exit.c: export abort() to modules

gcc -fisolate-erroneous-paths-dereference can generate calls to abort()
from modular code too.

[[e-mail]: drop duplicate exports of abort()]
Link: http://lkml.kernel.org/r/[e-mail]
Reported-by: Vineet Gupta <[e-mail]>
Cc: Sudip Mukherjee <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Alexey Brodkin <[e-mail]>
Cc: Russell King <[e-mail]>
Cc: Jose Abreu <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

arch/arm/kernel/traps.c

···
 	/* if that doesn't kill us, halt */
 	panic("Oops failed to kill thread");
 }
-EXPORT_SYMBOL(abort);
 
 void __init trap_init(void)
 {

arch/m32r/kernel/traps.c

···
 	/* if that doesn't kill us, halt */
 	panic("Oops failed to kill thread");
 }
-EXPORT_SYMBOL(abort);
 
 void __init trap_init(void)
 {

arch/unicore32/kernel/traps.c

···
 	/* if that doesn't kill us, halt */
 	panic("Oops failed to kill thread");
 }
-EXPORT_SYMBOL(abort);
 
 void __init trap_init(void)
 {

kernel/exit.c

···
 	/* if that doesn't kill us, halt */
 	panic("Oops failed to kill thread");
 }
+EXPORT_SYMBOL(abort);