add __MVS__ to list of systems that should default to UTF-8 in localcharset.c

[Mike Fulton]

Hi,

I would like to request a patch to localcharset.c to add __MVS__ to the
list of systems that should default to UTF-8.

On line 1137 to 1139, the code is currently:

# if (defined __APPLE__ && defined __MACH__) || defined __BEOS__ || defined
__HAIKU__
        codeset = "UTF-8";
# else

I would like to request the __MVS__ macro be added so that z/OS will
default to UTF-8, e.g.

# if (defined __APPLE__ && defined __MACH__) || defined __BEOS__ || defined
__HAIKU__ || defined __MVS__
        codeset = "UTF-8";
# else

I am currently using this patch for man-db so that it can correctly render
UTF-8 man pages.