make ecp_nistz256_point_add_vis3() local

fixes #8936
Reviewed-by: NRichard Levitte <levitte@openssl.org>
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9132)

(cherry picked from commit 861335001b99cfd665030c50ad37a663536a5c0f)

crypto/ec/asm/ecp_nistz256-sparcv9.pl

@@ -2301,7 +2301,6 @@ my ($Z1sqr, $Z2sqr) = ($Hsqr, $Rsqr);
 # !in1infty, !in2infty and result of check for zero.
 
 $code.=<<___;
-.globl	ecp_nistz256_point_add_vis3
 .align	32
 ecp_nistz256_point_add_vis3:
 	save	%sp,-STACK64_FRAME-32*18-32,%sp