cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration stdlib/putenv.c -o stdlib/putenv -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lintl -liconv
stdlib/putenv.c: In function ‘main’:
stdlib/putenv.c:11:14: error: implicit declaration of function ‘putenv’; did you mean ‘setenv’? [-Wimplicit-function-declaration]
   11 |         if ( putenv(envvar) )
      |              ^~~~~~
      |              setenv