Adjusted cf-support for exotic UNIX platforms

head -c 8 doesn't work on hpux 11.23 that we test on currently

dd count=1 bs=8 should work on all UNIX systems

tr on solaris needs LC_CTYPE=C as it can't handle binary data.
Silence not found sysctl command where it is not present.

Ticket: ENT-9786
Changelog: title

misc/cf-support

@@ -120,7 +120,7 @@ make_temp_dir()
   else
     # shellcheck disable=SC2021
     # ^^ legacy/POSIX requires square brackets
-    _tmp="/tmp/`tr -dc "[A-Z][a-z][0-9]" </dev/urandom | head -c 8`"
+    _tmp="/tmp/`LC_CTYPE=C tr -dc "[A-Z][a-z][0-9]" </dev/urandom | dd count=1 bs=8 2>/dev/null`"
     mkdir "$_tmp"
     echo "$_tmp"
   fi
@@ -150,7 +150,11 @@ mkdir -p "$tmpdir"
 
 echo "Analyzing CFEngine core dumps"
 _core_log="$tmpdir"/core-dump.log
-_sysctl_kernel_core_pattern="$(sysctl -n kernel.core_pattern)"
+if command -v sysctl >/dev/null; then
+  _sysctl_kernel_core_pattern="$(sysctl -n kernel.core_pattern)"
+else
+  _sysctl_kernel_core_pattern=""
+fi
 if expr "$_sysctl_kernel_core_pattern" : ".*/systemd-coredump.*" > /dev/null 2>&1; then
   echo "Found systemd-coredump used in sysctl kernel.core_pattern \"$_sysctl_kernel_core_pattern\""
   echo "Using coredumpctl to analyze CFEngine core dumps"