Support specifying variants in list-subports

Allow passing variants into list-subports by separating port name and
variants specification with an "@" sign. @ is not a valid character in
port names and should allow us to specify variants per port in the
buildbot's portlist.

When not using this new syntax, the output will look exactly as it did
before to avoid breaking the existing setup.

Closes: https://trac.macports.org/ticket/52742

mpbb-list-subports

@@ -9,7 +9,7 @@ list-subports-usage() {
     # "prog" is defined in mpbb-help.
     # shellcheck disable=SC2154
     cat <<EOF
-usage: $prog [<global opts>] list-subports [<opts>] <port> [<port2> [...]]
+usage: $prog [<global opts>] list-subports [<opts>] <port>[@(+|-)variant [...]] [<port2>[@(+|-)variant [...]] [...]]
 
 Print the name and subports of each given port to standard output.
 
@@ -25,7 +25,8 @@ EOF
 
 print-subports() {
     local archive_site=$1
-    local portname=$2
+    local portname=${2%%@*}
+    local portvariants=${2:${#portname}+1}
     local port
     local portgroup
     local ports
@@ -44,16 +45,15 @@ print-subports() {
         exclude=0
         exclude_reasons=()
 
-        # FIXME: this doesn't take selected variants into account
         # $thisdir is set in mpbb
         # shellcheck disable=SC2154
-        archive_path=$("${tclsh}" "${thisdir}/tools/archive-path.tcl" "${port}")
+        archive_path=$("${tclsh}" "${thisdir}/tools/archive-path.tcl" "${port}" "${portvariants}")
         if [[ -f "${archive_path}" ]]; then
             archive_basename=$(basename "${archive_path}")
             if curl -fIsL "${archive_site}/${port}/${archive_basename}" > /dev/null; then
                 exclude=1
                 exclude_reasons+=("it has already been built and uploaded")
-            elif ! "${tclsh}" "${option_jobs_dir}/port_binary_distributable.tcl" "${port}"; then
+            elif ! "${tclsh}" "${option_jobs_dir}/port_binary_distributable.tcl" "${port}" "${portvariants}"; then
                 exclude=1
                 exclude_reasons+=("it has already been built and is not distributable")
             fi
@@ -66,7 +66,7 @@ print-subports() {
             else
                 # $thisdir is set in mpbb
                 # shellcheck disable=SC2154
-                for portgroup in $("${tclsh}" "${thisdir}/tools/portgroups.tcl" "$port"); do
+                for portgroup in $("${tclsh}" "${thisdir}/tools/portgroups.tcl" "${port}" "${portvariants}"); do
                     if [ "$portgroup" = "obsolete-1.0" ]; then
                         exclude=1
                         exclude_reasons+=("it includes the obsolete 1.0 PortGroup")
@@ -76,7 +76,7 @@ print-subports() {
         fi
 
         if [[ $exclude -eq 0 && ("${os_version}" = "10.6" || "${os_version}" = "10.5") ]]; then
-            supported_archs=$("${tclsh}" "${thisdir}/tools/supported-archs.tcl" "${port}")
+            supported_archs=$("${tclsh}" "${thisdir}/tools/supported-archs.tcl" "${port}" "${portvariants}")
             if [[ -n "${supported_archs}" ]]; then
                 is_64bit_capable="$(sysctl -n hw.cpu64bit_capable)"
                 if [[ "${os_version}" = "10.6" && "${is_64bit_capable}" = "0" && ! ("${supported_archs}" == *"x86_64"* && "${supported_archs}" == *"i386"*) ]]; then
@@ -90,7 +90,11 @@ print-subports() {
         fi
 
         if [ $exclude -eq 0 ]; then
-            echo "$port"
+            if [ -n "${portvariants}" ]; then
+                echo "${port}@${portvariants}"
+            else
+                echo "$port"
+            fi
         else
             if [ ${#exclude_reasons[@]} -eq 1 ]; then
                 echo >&2 "Excluding '${port}' because ${exclude_reasons[0]}."