Slightly sped up the linux standalone bundle

Reduce the number of directories listed in libdirs, which makes the linker
check a lot less dead ends looking for directories.

Eliminated some directories that didn't really contain shared libraries,
or only contained the linker.

That left only 2, one in lib and one in usr/lib, so consolidate those two.

Doing it this way, rather than just consolidating all libs that might exist
into a single directory means that, if there are optimised versions of some
libs, eg in lib/subarch/foo.so, and lib/subarch2/foo.so, they don't get
moved around in a way that would make the linker pick the wrong one.

doc/todo/may_be___40__again__41___to_prelink_or_somehow_avoid_all_the_failing_opens__63__/comment_13_5d65192366f7690c22d1a209fb1e8f78._comment

@@ -0,0 +1,20 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 13"""
+ date="2020-07-31T17:41:55Z"
+ content="""
+`git-annex init` runs git something like 30 times, so it's close to the worst
+case for a single git-annex command, other than when smudge filters are run.
+
+I tried inlining runshell into both git and git-annex scripts, thinking
+that the overhead of starting the second shell script might be measurable.
+It was not; I saw `git-annex init` taking 0.10-0.14s before and after.
+
+I also tried trimming out some parts of the script that normally
+don't run, like the android support, but that didn't speed it up.
+
+With the consolidated lib dirs, I did see `git-annex init` drop to 0.07-0.10s.
+
+Ok, I found a way to consolidate the directories that will not include
+directories for optimised libs. Implemented that.
+"""]]