useradd.bbclass: Fix order of postinst-useradd-*

postinst-useradd-* haven't been running in order of dependency.

This patch is reworked from Piotr Łobacz's patch and fixes:

https://bugzilla.yoctoproject.org/show_bug.cgi?id=15084
https://bugzilla.yoctoproject.org/show_bug.cgi?id=13904

basepasswd_sysroot_postinst in base-passwd can install postinst-useradd-*
scripts with any order. Sometimes this means, for example a useradd postinst
will attempt to run without the corresponding group postinst causing errors.
This patch ensures that we first run groupadd, then useradd and then
group membership.

[RP: Tweaked to avoid removing previous fixes and for whitespace/style issues
     Also ensure the scripts are changed to execute with -e to highlight errors]

(From OE-Core rev: 322ef726132a47d977d2c6ee41de5358f1e85994)

Signed-off-by: Eilís 'pidge' Ní Fhlannagáin <pidge@baylibre.com>
Signed-off-by: Piotr Łobacz <p.lobacz@welotec.com>
Signed-off-by: Jan Górski <j.gorski@welotec.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes-global/staging.bbclass

@@ -245,7 +245,7 @@ def staging_populate_sysroot_dir(targetsysroot, nativesysroot, native, d):
                         continue
 
     staging_processfixme(fixme, targetdir, targetsysroot, nativesysroot, d)
-    for p in postinsts:
+    for p in sorted(postinsts):
         bb.note("Running postinst {}, output:\n{}".format(p, subprocess.check_output(p, shell=True, stderr=subprocess.STDOUT)))
 
 #
@@ -629,7 +629,7 @@ python extend_recipe_sysroot() {
     for f in fixme:
         staging_processfixme(fixme[f], f, recipesysroot, recipesysrootnative, d)
 
-    for p in postinsts:
+    for p in sorted(postinsts):
         bb.note("Running postinst {}, output:\n{}".format(p, subprocess.check_output(p, shell=True, stderr=subprocess.STDOUT)))
 
     for dep in manifests: