patch 8.1.0363: internal diff isn't used by default as advertised
Problem: Internal diff isn't used by default as advertised.
Solution: Add "internal" to the default value of 'diffopt'.
Also add couple of files missing from the distribution.
diff --git a/Filelist b/Filelist
index 343a2bd..59415d3 100644
--- a/Filelist
+++ b/Filelist
@@ -273,6 +273,8 @@
src/libvterm/t/92lp1640917.test \
src/libvterm/t/harness.c \
src/libvterm/t/run-test.pl \
+ src/xdiff/COPYING \
+ src/xdiff/README.txt \
src/xdiff/xdiff.h \
src/xdiff/xdiffi.c \
src/xdiff/xdiffi.h \