scripts/populate: fix handling the forced libraries list-file

If a list-file is used, then each library in the file will be handled
twice (not a real issue, as the second iteration will find the library
already present, just avoid doing the job twice).

scripts/populate.in

@@ -206,6 +206,7 @@ do_add_lib() {
 pushd "${CT_ROOT_DST_DIR}" >/dev/null
 
 # First of, copy the forced libraries into the working copy
+lib_list=
 if [ -n "${CT_LIB_FILE}" ]; then
     lib_list=$("${sed}" -r -e ':loop; s/#.*//;'         \
                            -e 's/[[:space:]]+//g;'      \
@@ -213,9 +214,6 @@ if [ -n "${CT_LIB_FILE}" ]; then
                            -e '/$/N; s/\n//; tloop;'    \
                         "${CT_LIB_FILE}"
               )
-    CT_LIB_LIST=$(echo "${CT_LIB_LIST}:${lib_list}"             \
-                  |"${sed}" -r -e 's/:+/:/g; s/^:+//; s/:+$//;' \
-                 )
 fi
 CT_LIB_LIST=$(echo "${CT_LIB_LIST}:${lib_list}"             \
               |"${sed}" -r -e 's/^:+//; s/:+$//; s/:+/ /g;' \