Verified that both programs compile with
gcc -I. -I../include -lsecp256k1 -c -W -Wextra -Wall -Werror -ansi -pedantic lax_der_privatekey_parsing.c
gcc -I. -I../include -lsecp256k1 -c -W -Wextra -Wall -Werror -ansi -pedantic lax_der_parsing.c