xbps-src: use "virtual?" keyword to declare virtual runtime dependencies.

The syntax "pkg?vpkg" can be used in hostmakedepends, makedepends and depends;
but the "virtual" keyword can be declared specifically for runtime dependencies
(depends).

common/hooks/post-install/04-generate-runtime-deps.sh

@@ -156,6 +156,7 @@ hook() {
 
 	if [ -n "$run_depends" ]; then
 		echo "$run_depends" > ${PKGDESTDIR}/rdeps
+		sed 's,virtual?,,g' -i ${PKGDESTDIR}/rdeps
 	fi
 	if [ -n "${sorequires}" ]; then
 		echo "${sorequires}" > ${PKGDESTDIR}/shlib-requires

common/xbps-src/shutils/build_dependencies.sh

@@ -180,6 +180,11 @@ install_pkg_deps() {
     for i in ${build_depends} "RDEPS" ${run_depends}; do
         [ "$i" = "RDEPS" ] && rundep="runtime" && continue
         _realpkg="${i%\?*}"
+        if [ "${_realpkg}" = "virtual" ]; then
+            # ignore virtual dependencies
+            echo "   [${rundep:-target}] ${i#*\?}: virtual dependency."
+            continue
+        fi
         pkgn=$($XBPS_UHELPER_CMD getpkgdepname "${_realpkg}")
         if [ -z "$pkgn" ]; then
             pkgn=$($XBPS_UHELPER_CMD getpkgname "${_realpkg}")

common/xbps-src/shutils/common.sh

@@ -391,7 +391,7 @@ setup_pkg() {
 }
 
 setup_pkg_depends() {
-    local pkg="$1" j _pkgdepname _pkgdep _depname
+    local pkg="$1" j _pkgdepname _pkgdep _rpkgname _depname
 
     if [ -n "$pkg" ]; then
         # subpkg
@@ -401,6 +401,7 @@ setup_pkg_depends() {
     fi
 
     for j in ${depends}; do
+        _rpkgname="${j%\?*}"
         _depname="${j#*\?}"
         _pkgdepname="$($XBPS_UHELPER_CMD getpkgdepname ${_depname} 2>/dev/null)"
         if [ -z "${_pkgdepname}" ]; then
@@ -412,7 +413,11 @@ setup_pkg_depends() {
         else
             _pkgdep="${_depname}"
         fi
-        run_depends+=" ${_pkgdep}"
+        if [ "${_rpkgname}" = "virtual" ]; then
+            run_depends+=" virtual?${_pkgdep}"
+        else
+            run_depends+=" ${_pkgdep}"
+        fi
     done
     for j in ${hostmakedepends}; do
         _depname="${j%\?*}"