cc -pthread   -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations math/M_EGAMMA.c -o math/M_EGAMMA -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt  -lintl -liconv
math/M_EGAMMA.c:8:21: error: ‘M_EGAMMA’ undeclared here (not in a function)
    8 | double  const foo = M_EGAMMA;
      |                     ^~~~~~~~