libbpf: Fix ELF symbol visibility update logic

mainline inclusion
from mainline-5.14-rc1
commit 247b8634
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=247b8634e6446dbc8024685f803290501cba226f

-------------------------------------------------

Fix silly bug in updating ELF symbol's visibility.

Fixes: a4634922 ("libbpf: Add linker extern resolution support for functions and global variables")
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210507054119.270888-6-andrii@kernel.org
(cherry picked from commit 247b8634)
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

tools/lib/bpf/linker.c

@@ -1788,7 +1788,7 @@ static void sym_update_visibility(Elf64_Sym *sym, int sym_vis)
 	/* libelf doesn't provide setters for ST_VISIBILITY,
 	 * but it is stored in the lower 2 bits of st_other
 	 */
-	sym->st_other &= 0x03;
+	sym->st_other &= ~0x03;
 	sym->st_other |= sym_vis;
 }