getdtablesize.2, sigqueue.2, clock_getres.3, clock_gettime.3, clock_settime.3, attr.5, numa_maps.5: Remove old links

These are all links that were created several years ago, mainly
when pages were migrated to different sections, in order to
allow the 'man' commands using the old section numbers to work.
However, the plan was always to eventually remove them, after
allowing people who cared to get used to the new section numbers.
Now, after 5+ years in each case, it's time to remove
these links.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/getdtablesize.2

@@ -1,2 +0,0 @@
-.so man3/getdtablesize.3
-.\" Created 2013-02-05; will eventually be removed

man2/sigqueue.2

@@ -1,2 +0,0 @@
-.so man3/sigqueue.3
-.\" FIXME . this link will eventually be removed (created Sep 2011)

man3/clock_getres.3

@@ -1,3 +0,0 @@
-.so man2/clock_getres.2
-.\" This link provided in Section 3 because, by historical accident,
-.\" the page was originally in Section 3 -- mtk, Feb 2009

man3/clock_gettime.3

@@ -1,3 +0,0 @@
-.so man2/clock_getres.2
-.\" This link provided in Section 3 because, by historical accident,
-.\" the page was originally in Section 3 -- mtk, Feb 2009

man3/clock_settime.3

@@ -1,3 +0,0 @@
-.so man2/clock_getres.2
-.\" This link provided in Section 3 because, by historical accident,
-.\" the page was originally in Section 3 -- mtk, Feb 2009

man5/attr.5

@@ -1,2 +0,0 @@
-.so man7/xattr.7
-.\" Page was imported from 'attr' project which had it in Section 5

man5/numa_maps.5

@@ -1,5 +0,0 @@
-.so man7/numa.7
-.\" As part of the numactl() package, the /proc/PID/numa_maps
-.\" documentation was in a numa_maps.5 page; this link
-.\" ensures that "man 5 numa_maps" still works.
-.\" Eventually, we may want to remove it -- mtk, Aug 2008