bpo-40334: Fix builds outside the source directory and regenerate autoconf files (GH-19667)

diff --git a/configure b/configure
index d3e8149..29d5f4c 100755
--- a/configure
+++ b/configure
@@ -16746,7 +16746,7 @@
 done
 
 
-SRCDIRS="Parser Objects Python Modules Modules/_io Programs"
+SRCDIRS="Parser Parser/pegen Objects Python Modules Modules/_io Programs"
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for build directories" >&5
 $as_echo_n "checking for build directories... " >&6; }
 for dir in $SRCDIRS; do