workaround for /lib/modules on ALT and do list uniq

etercifs/checkmodule.sh

@@ -47,7 +47,8 @@ check_build_module()
     echo "====================================================================="
     echo "Check build etercifs module for all found kernels"
     BUILTLIST=
-    for KERNSRC in $(list_kernel_headers) ; do
+    # Note: we can skip any duplicates here
+    for KERNSRC in $(list_kernel_headers | xargs -n1 realpath | sort -u) ; do
             echo "---------------------------------------------------------------------"
             detect_kernel
             if [ -z "$KERNELVERSION" ] ; then

etercifs/functions.sh

@@ -100,7 +100,10 @@ create_builddir()
 list_kernel_headers()
 {
     local LM
-    for LM in `ls -d /lib/modules/*/build` ; do
+    local LMP="/lib/modules/*/build"
+    # forbidden on ALT
+    test -x /lib/modules || LMP="/usr/src/linux-*"
+    for LM in `ls -d $LMP` ; do
         [ -r "$LM" ] || continue
         [ -L $(readlink $LM) ] && continue
         [ -f $LM/.config ] || continue