patch 8.2.3666: libvterm is outdated

Problem:    Libvterm is outdated.
Solution:   Include patches from revision 769 to revision 789.
diff --git a/src/libvterm/Makefile b/src/libvterm/Makefile
index be01dd0..2f83e0d 100644
--- a/src/libvterm/Makefile
+++ b/src/libvterm/Makefile
@@ -37,7 +37,7 @@
 HFILES_INT=$(sort $(wildcard src/*.h)) $(HFILES)
 
 VERSION_MAJOR=0
-VERSION_MINOR=1
+VERSION_MINOR=2
 
 VERSION_CURRENT=0
 VERSION_REVISION=0
@@ -97,7 +97,7 @@
 	install -d $(DESTDIR)$(INCDIR)
 	install -m644 $(HFILES) $(DESTDIR)$(INCDIR)
 	install -d $(DESTDIR)$(LIBDIR)/pkgconfig
-	sed -e "s,@PREFIX@,$(PREFIX)," -e "s,@LIBDIR@,$(LIBDIR)," -e "s,@VERSION@,$(VERSION)," <vterm.pc.in >$(DESTDIR)$(LIBDIR)/pkgconfig/vterm.pc
+	sed -e "s,@INCDIR@,$(INCDIR)," -e "s,@LIBDIR@,$(LIBDIR)," -e "s,@VERSION@,$(VERSION)," <vterm.pc.in >$(DESTDIR)$(LIBDIR)/pkgconfig/vterm.pc
 
 install-lib: $(LIBRARY)
 	install -d $(DESTDIR)$(LIBDIR)