patch 8.1.2062: the mouse code is spread out

Problem:    The mouse code is spread out.
Solution:   Move all the mouse code to mouse.c. (Yegappan Lakshmanan,
            closes #4959)
diff --git a/src/auto/configure b/src/auto/configure
index 8dcad0b..c9b370c 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -7909,7 +7909,7 @@
 
   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"
 
-  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"
+  TERM_OBJ="objects/encoding.o objects/keyboard.o objects/termmouse.o objects/parser.o objects/pen.o objects/termscreen.o objects/state.o objects/unicode.o objects/vterm.o"
 
 fi