patch 8.1.0914: code related to findfile() is spread out

Problem:    Code related to findfile() is spread out.
Solution:   Put findfile() related code into a new source file. (Yegappan
            Lakshmanan, closes #3934)
diff --git a/src/Make_dice.mak b/src/Make_dice.mak
index 57aed47..ffce805 100644
--- a/src/Make_dice.mak
+++ b/src/Make_dice.mak
@@ -46,6 +46,7 @@
 	ex_getln.c \
 	farsi.c \
 	fileio.c \
+	findfile.c \
 	fold.c \
 	getchar.c \
 	hardcopy.c \
@@ -105,6 +106,7 @@
 	o/ex_getln.o \
 	o/farsi.o \
 	o/fileio.o \
+	o/findfile.o \
 	o/fold.o \
 	o/getchar.o \
 	o/hardcopy.o \
@@ -203,6 +205,8 @@
 
 o/fileio.o:	fileio.c  $(SYMS)
 
+o/findfile.o:	findfile.c  $(SYMS)
+
 o/fold.o:	fold.c  $(SYMS)
 
 o/getchar.o: getchar.c	$(SYMS)