patch 8.1.1985: code for dealing with paths is spread out

Problem:    Code for dealing with paths is spread out.
Solution:   Move path related functions from misc1.c to filepath.c.
            Remove NO_EXPANDPATH.
diff --git a/src/globals.h b/src/globals.h
index 46dedae..adf8b63 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -1183,6 +1183,8 @@
 extern char_u *compiled_sys;
 #endif
 
+EXTERN char_u	*homedir INIT(= NULL);
+
 // When a window has a local directory, the absolute path of the global
 // current directory is stored here (in allocated memory).  If the current
 // directory is not a local directory, globaldir is NULL.