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/proto/scriptfile.pro b/src/proto/scriptfile.pro
index c56b1c6..8104b27 100644
--- a/src/proto/scriptfile.pro
+++ b/src/proto/scriptfile.pro
@@ -8,6 +8,7 @@
 void load_start_packages(void);
 void ex_packloadall(exarg_T *eap);
 void ex_packadd(exarg_T *eap);
+void remove_duplicates(garray_T *gap);
 int ExpandRTDir(char_u *pat, int flags, int *num_file, char_u ***file, char *dirnames[]);
 int ExpandPackAddDir(char_u *pat, int *num_file, char_u ***file);
 void ex_source(exarg_T *eap);