cc -O2 -pipe  -pthread  -Wall -Wextra -Werror=implicit-function-declaration iconv/iconv_close.c -o iconv/iconv_close -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread 
iconv/iconv_close.c:3:10: fatal error: 'iconv.h' file not found
    3 | #include <iconv.h>
      |          ^~~~~~~~~
1 error generated.