tests: fix -Werror=discarded-qualifiers errors in check_public.c
check_public.c: In function ‘parse_display_pass’:
check_public.c:32:32: error: passing argument 1 of ‘putenv’ discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
32 | putenv("DISPLAY=");
| ^~~~~~~~~~
In file included from check_public.c:4:
/usr/include/stdlib.h:148:19: note: expected ‘char *’ but argument is of type ‘const char *’
148 | extern int putenv(char *);
| ^~~~~~
check_public.c:57:16: error: passing argument 1 of ‘putenv’ discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
57 | putenv("DISPLAY=");
| ^~~~~~~~~~
/usr/include/stdlib.h:148:19: note: expected ‘char *’ but argument is of type ‘const char *’
148 | extern int putenv(char *);
| ^~~~~~
check_public.c: In function ‘parse_display_fail’:
check_public.c:73:32: error: passing argument 1 of ‘putenv’ discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
73 | putenv("DISPLAY=");
| ^~~~~~~~~~
/usr/include/stdlib.h:148:19: note: expected ‘char *’ but argument is of type ‘const char *’
148 | extern int putenv(char *);
| ^~~~~~
check_public.c:99:16: error: passing argument 1 of ‘putenv’ discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
99 | putenv("DISPLAY=");
| ^~~~~~~~~~
/usr/include/stdlib.h:148:19: note: expected ‘char *’ but argument is of type ‘const char *’
148 | extern int putenv(char *);
| ^~~~~~
check_public.c: In function ‘public_suite’:
check_public.c:244:16: error: passing argument 1 of ‘putenv’ discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
244 | putenv("DISPLAY=");
| ^~~~~~~~~~
/usr/include/stdlib.h:148:19: note: expected ‘char *’ but argument is of type ‘const char *’
148 | extern int putenv(char *);
| ^~~~~~
cc1: all warnings being treated as errors