patch 8.1.0379: build dependencies are incomplete

Problem:    Build dependencies are incomplete.
Solution:   Update the build dependencies, mainly for xdiff.  Adjust object
            directory for libvterm and xdiff.
diff --git a/src/configure.ac b/src/configure.ac
index 9f17b9c..2a31f41 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -2114,9 +2114,9 @@
 fi
 if test "$enable_terminal" = "yes" -a "$enable_channel" = "yes"; then
   AC_DEFINE(FEAT_TERMINAL)
-  TERM_SRC="libvterm/src/encoding.c libvterm/src/keyboard.c libvterm/src/mouse.c libvterm/src/parser.c libvterm/src/pen.c libvterm/src/screen.c libvterm/src/state.c libvterm/src/unicode.c libvterm/src/vterm.c"
+  TERM_SRC="libvterm/src/encoding.c libvterm/src/keyboard.c libvterm/src/mouse.c libvterm/src/parser.c libvterm/src/pen.c libvterm/src/termscreen.c libvterm/src/state.c libvterm/src/unicode.c libvterm/src/vterm.c"
   AC_SUBST(TERM_SRC)
-  TERM_OBJ="objects/term_encoding.o objects/term_keyboard.o objects/term_mouse.o objects/term_parser.o objects/term_pen.o objects/term_screen.o objects/term_state.o objects/term_unicode.o objects/term_vterm.o"
+  TERM_OBJ="objects/encoding.o objects/keyboard.o objects/mouse.o objects/parser.o objects/pen.o objects/termscreen.o objects/state.o objects/unicode.o objects/vterm.o"
   AC_SUBST(TERM_OBJ)
 fi