patch 8.1.1391: no popup window support

Problem:    No popup window support.
Solution:   Add initial code for popup windows.  Add the 'wincolor' option.
diff --git a/src/Makefile b/src/Makefile
index ff5ae10..d74eac4 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1620,6 +1620,7 @@
 	os_unix.c \
 	auto/pathdef.c \
 	popupmnu.c \
+	popupwin.c \
 	pty.c \
 	quickfix.c \
 	regexp.c \
@@ -1734,6 +1735,7 @@
 	objects/os_unix.o \
 	objects/pathdef.o \
 	objects/popupmnu.o \
+	objects/popupwin.o \
 	objects/pty.o \
 	objects/quickfix.o \
 	objects/regexp.o \
@@ -1873,6 +1875,7 @@
 	os_mac_conv.pro \
 	os_unix.pro \
 	popupmnu.pro \
+	popupwin.pro \
 	pty.pro \
 	quickfix.pro \
 	regexp.pro \
@@ -3208,6 +3211,9 @@
 objects/popupmnu.o: popupmnu.c
 	$(CCC) -o $@ popupmnu.c
 
+objects/popupwin.o: popupwin.c
+	$(CCC) -o $@ popupwin.c
+
 objects/pty.o: pty.c
 	$(CCC) -o $@ pty.c
 
@@ -3612,6 +3618,10 @@
  auto/osdef.h ascii.h keymap.h term.h macros.h option.h beval.h \
  proto/gui_beval.pro structs.h regexp.h gui.h alloc.h ex_cmds.h spell.h \
  proto.h globals.h
+objects/popupwin.o: popupwin.c vim.h protodef.h auto/config.h feature.h os_unix.h \
+ auto/osdef.h ascii.h keymap.h term.h macros.h option.h beval.h \
+ proto/gui_beval.pro structs.h regexp.h gui.h alloc.h ex_cmds.h spell.h \
+ proto.h globals.h
 objects/pty.o: pty.c vim.h protodef.h auto/config.h feature.h os_unix.h \
  auto/osdef.h ascii.h keymap.h term.h macros.h option.h beval.h \
  proto/gui_beval.pro structs.h regexp.h gui.h alloc.h ex_cmds.h spell.h \