xbps-src: run pre-pkg hooks in the install to destdir target.

The prepare-32bit hook has been moved to the pre-pkg stage and now
those hooks are executed as part of the install phase. That means that
pre-pkg hooks are now independently run for the subpkgs and the sourcepkg
after the install-destdir phase and pre/do/install hooks.

As bonus, finally correct rdeps can now be collected for the 32bit pkgs
and works for all them, without the need to sort the order of subpkgs!

common/xbps-src/libexec/xbps-src-prepkg.sh

@@ -0,0 +1,43 @@
+#!//bin/bash
+#
+# vim: set ts=4 sw=4 et:
+#
+# Passed arguments:
+#	$1 - pkgname [REQUIRED]
+#	$2 - cross target [OPTIONAL]
+
+if [ $# -lt 1 -o $# -gt 2 ]; then
+    echo "$(basename $0): invalid number of arguments: pkgname [cross-target]"
+    exit 1
+fi
+
+PKGNAME="$1"
+XBPS_CROSS_BUILD="$2"
+
+. $XBPS_SHUTILSDIR/common.sh
+
+for f in $XBPS_COMMONDIR/helpers/*.sh; do
+    source_file "$f"
+done
+
+setup_pkg "$PKGNAME" $XBPS_CROSS_BUILD
+
+for f in $XBPS_COMMONDIR/environment/install/*.sh; do
+    source_file "$f"
+done
+
+# If it's a subpkg execute the pkg_install() function.
+if [ "$sourcepkg" != "$PKGNAME" ]; then
+    # Source all subpkg environment setup snippets.
+    for f in ${XBPS_COMMONDIR}/environment/setup-subpkg/*.sh; do
+        source_file "$f"
+    done
+    ${PKGNAME}_package
+    pkgname=$PKGNAME
+fi
+
+setup_pkg_depends $pkgname
+
+run_pkg_hooks pre-pkg
+
+exit 0