[PATCH] vdso: Improve cmd_vdso_check to check all dynamic relocations

[Fangrui Song]

On 2022-08-30, Fangrui Song wrote:
>The actual intention is that no dynamic relocation exists. However, some
>GNU ld ports produce unneeded R_*_NONE. (If a port is not care enough to
>determine the exact .rel[a].dyn size, the trailing zeros become R_*_NONE
>relocations. E.g. powerpc64le ld as of 2.38 has the issue with
>defconfig.) R_*_NONE are generally no-op in the dynamic loaders. So just
>ignore them.
>
>With the change, we can remove ARCH_REL_TYPE_ABS. ARCH_REL_TYPE_ABS is a
>bit misnomer as ports may check RELAVETIVE/GLOB_DAT/JUMP_SLOT which are
>not called "absolute relocations". (The patch is motivated by the arm64
>port missing R_AARCH64_RELATIVE.)
>
>While here, replace "egrep" with "grep" as "egrep" is deprecated in GNU
>grep 3.7.
>
>Signed-off-by: Fangrui Song <maskray at google.com>
>---
>[...]
>

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