Actually constify showbuf()

Geeze, this is ugly.
14 jobs for master in 7 minutes and 58 seconds (queued for 11 seconds)
Status Job ID Name Coverage
  Build
failed #30586
FreeBSD
jsdoor-freebsd

00:03:47

failed #30587
Linux
jsdoor-linux

00:07:30

failed #30589
FreeBSD
jsdoor-windows

00:01:31

failed #30581
FreeBSD
sbbs-freebsd

00:03:29

failed #30576
Linux
sbbs-linux

00:06:55

failed #30579
Windows
sbbs-windows

00:02:36

passed #30588
FreeBSD
sexpots-freebsd

00:00:12

passed #30577
Linux
sexpots-linux

00:00:25

passed #30580
Windows
sexpots-windows

00:00:33

passed #30584
FreeBSD
syncdraw-freebsd

00:00:26

passed #30585
Linux
syncdraw-linux

00:01:04

passed #30582
FreeBSD
syncterm-freebsd

00:01:01

passed #30578
Linux
syncterm-linux

00:02:55

passed #30583
FreeBSD
syncterm-windows

00:01:46

 
Name Stage Failure
failed
jsdoor-linux Build
  utf8_to_cp437_str(buf);
^~~~~~~~~~~~~~~~~
In file included from js_global.c:30:
/home/gitlab-runner/builds/vLEE6HYB/1/main/sbbs/src/sbbs3/../encode/utf8.h:71:5: note: declared here
int utf8_to_cp437_str(const char *src, char *dest, size_t maxlen, unsigned char minval, size_t *outlen);
^~~~~~~~~~~~~~~~~
make: *** [/home/gitlab-runner/builds/vLEE6HYB/1/main/sbbs/src/sbbs3/../build/Common.gmake:462: gcc.linux.x64.obj.release-mt/js_global.o] Error 1
Cleaning up file based variables
ERROR: Job failed: exit status 1
failed
sbbs-linux Build
     ^~~~~~~~~~~~~~~~~
In file included from sbbs.h:291,
from atcodes.cpp:22:
str_util.h:70:18: note: previous declaration ‘char* utf8_to_cp437_str(char*)’
DLLEXPORT char * utf8_to_cp437_str(char* str);
^~~~~~~~~~~~~~~~~
make: *** [/home/gitlab-runner/builds/vLEE6HYB/2/main/sbbs/src/sbbs3/../build/Common.gmake:467: gcc.linux.x64.obj.release-mt/atcodes.o] Error 1
Cleaning up file based variables
ERROR: Job failed: exit status 1
failed
jsdoor-freebsd Build
int utf8_to_cp437_str(const char *src, char *dest, size_t maxlen, unsigned char minval, size_t *outlen);
^
./str_util.h:70:18: note: previous declaration is here
DLLEXPORT char * utf8_to_cp437_str(char* str);
^
1 error generated.
gmake: *** [/var/tmp/gitlab_runner/builds/TkL89aUh/4/main/sbbs/src/sbbs3/../build/Common.gmake:462: clang.freebsd.amd64.obj.release-mt/js_global.o] Error 1
Cleaning up file based variables
ERROR: Job failed: exit status 1
failed
sbbs-freebsd Build
int utf8_to_cp437_str(const char *src, char *dest, size_t maxlen, unsigned char minval, size_t *outlen);
~~~ ^
./str_util.h:70:18: note: previous declaration is here
DLLEXPORT char * utf8_to_cp437_str(char* str);
~~~~~~ ^
1 error generated.
gmake: *** [/var/tmp/gitlab_runner/builds/TkL89aUh/1/main/sbbs/src/sbbs3/../build/Common.gmake:467: clang.freebsd.amd64.obj.release-mt/atcodes.o] Error 1
Cleaning up file based variables
ERROR: Job failed: exit status 1
failed
sbbs-windows Build

77 Warning(s)
15 Error(s)

Time Elapsed 00:02:06.28

!ERROR(s) occurred
Cleaning up file based variables
ERROR: Job failed: exit status 1
failed
jsdoor-windows Build
  utf8_to_cp437_str(buf);
^
In file included from js_global.c:30:0:
/var/tmp/gitlab_runner/builds/TkL89aUh/5/main/sbbs/src/sbbs3/../encode/utf8.h:71:5: note: declared here
int utf8_to_cp437_str(const char *src, char *dest, size_t maxlen, unsigned char minval, size_t *outlen);
^
gmake: *** [/var/tmp/gitlab_runner/builds/TkL89aUh/5/main/sbbs/src/sbbs3/../build/Common.gmake:462: gcc.win32.amd64.obj.release-mt/js_global.o] Error 1
Cleaning up file based variables
ERROR: Job failed: exit status 1