merge r3138, r3139, r3157, r3158, r3159, r3164, r3165,

merge r3138, r3139, r3157, r3158, r3159, r3164, r3165,
      r3202, r3203, r3383, r3388, r3417, r3418:

Win32 (mostly) and some Unix file related fixes:

*) preserve errno while ngx_free()
*) win32 ngx_file_info() utf8 support
*) delete Win95 code
*) log file name for read/write errors
*) test incomplete WriteFile()
*) handle short pwrite() to log an error cause: ENOSPC, EDQUOT, or EFBIG
*) uniform ngx_directio_on/off() interface with other file functions
*) do not create Win32 drive letter in ngx_create_full_path()
*) ignore EACCES errors for top level directories in ngx_create_full_path()
*) fix Win32 error messages when an temporary file replaces an existent file:
   *) do not rename an already renamed file
   *) now ngx_win32_rename_file() returns error code
   *) do not log failure inside ngx_win32_rename_file()
*) fix Win32 error message when an temporary file replaces an existent file:
   return at once if ngx_win32_rename_file() was not failed
   and do not try to delete already the renamed temporary file
*) skip URI trailing spaces under Win32
*) disable Win32 short file names