syscalls/mmap07: Remove the test #51

Job	Run time
job (debian:stable, gcc, i386)	7m 54s
job (debian:stable, ppc64el, powerpc64le-linux-gnu-gcc, 1, out, cross-compile)	8m 3s
job (debian:stable, arm64, aarch64-linux-gnu-gcc, 1, out, cross-compile)	6m 34s
job (debian:stable, s390x, s390x-linux-gnu-gcc, 1, out, cross-compile)	6m 56s
job (alpine:latest, gcc, asciidoctor)	5m 43s
job (debian:stable, gcc, out, minimal)	7m 30s
job (fedora:latest, clang, 1, asciidoctor-pdf)	9m 1s
job (centos:7, gcc, asciidoc-pdf, out)	5m 14s
job (debian:testing, gcc, asciidoctor-pdf)	7m 44s
job (debian:oldstable, clang)	9m 11s
job (opensuse/leap, gcc, asciidoc-pdf)	6m 49s
job (debian:oldstable, gcc, asciidoctor)	8m 49s
job (debian:testing, clang, asciidoctor-pdf)	12m 6s
job (ubuntu:jammy, gcc, asciidoctor, out)	7m 0s
job (ubuntu:bionic, gcc, asciidoc-pdf)	8m 16s
	1h 56m 50s

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