i386: fix .size of _init/_fini

binutils-2.21 barf on .size that do not evaluate to const, so use
the section size and not a function that is not visible here.

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

libc/sysdeps/linux/i386/crtn.S

@@ -6,7 +6,7 @@
 	popl	%ebx
 	popl	%ebp
 	ret
-.size _init,.-_init
+.size _init,.-.init
 
 
 
@@ -16,7 +16,7 @@
 	popl	%ebx
 	popl	%ebp
 	ret
-.size _fini,.-_fini
+.size _fini,.-.fini