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/Filelist b/Filelist
index cd9cbf3..211b487 100644
--- a/Filelist
+++ b/Filelist
@@ -41,6 +41,7 @@
 		src/farsi.h \
 		src/feature.h \
 		src/fileio.c \
+		src/findfile.c \
 		src/fold.c \
 		src/getchar.c \
 		src/globals.h \
@@ -170,6 +171,7 @@
 		src/proto/ex_getln.pro \
 		src/proto/farsi.pro \
 		src/proto/fileio.pro \
+		src/proto/findfile.pro \
 		src/proto/fold.pro \
 		src/proto/getchar.pro \
 		src/proto/gui.pro \