makepkg: append pkgbase to BUILDDIR if specified

This means multiple packages can be build using the same BUILDDIR
without their source files all ending up extracted in the same
directory.  Fixes FS#28417.

Signed-off-by: Allan McRae <allan@archlinux.org>
Signed-off-by: Dan McGee <dan@archlinux.org>

scripts/makepkg.sh.in

@@ -2061,8 +2061,6 @@ if [[ ! -w $BUILDDIR ]]; then
 	plain "$(gettext "Aborting...")"
 	exit 1
 fi
-srcdir="$BUILDDIR/src"
-pkgdir="$BUILDDIR/pkg"
 
 PKGDEST=${_PKGDEST:-$PKGDEST}
 PKGDEST=${PKGDEST:-$startdir} #default to $startdir if undefined
@@ -2159,6 +2157,14 @@ fi
 pkgbase=${pkgbase:-${pkgname[0]}}
 epoch=${epoch:-0}
 
+if [[ $BUILDDIR = "$startdir" ]]; then
+	srcdir="$BUILDDIR/src"
+	pkgdir="$BUILDDIR/pkg"
+else
+	srcdir="$BUILDDIR/$pkgbase/src"
+	pkgdir="$BUILDDIR/$pkgbase/pkg"
+fi
+
 if (( GENINTEG )); then
 	mkdir -p "$srcdir"
 	chmod a-s "$srcdir"