When the source file permission is r--r--r--, truncate and setutimes
AFTER chmod fail due to permission deined. So, do chmod after truncate
and setutimes.
split message print fuctions (mpr_*), strerrno, and mscp_get/set_error
into print.c/h and strerrno.c/h.
ToDo: revise usages of priv_set_errv and pr_* functions.
musllibc does not implement GLOB_ALTDIRFUNC, so do not call
glob for remote sides when libc is musl.
test_e2e.py skips test_glob_src_path when running on alpine.
Previously wrapper functions for open(), opendir(), and stat(), etc,
are implemneted in path.h, and now they are in fileops.h and fileops.c.
This commit is a reparation for remote glob.