определить язык ОС из C #

Если вы находитесь на RHEL и хотите создать завиток (например, v7.45) со статически связанными libs (автономный двоичный код), вы также можете:

yum install openssl-devel # for headers and libraries
# run `./buildconf` if you cloned curl git repo
./configure --with-ssl=/usr/include/openssl --disable-shared
make

Ваш двоичный файл будет создан на ./src/curl.

openssl-devel версия 1.0.1e устанавливает:

/usr/include/openssl
/usr/include/openssl/aes.h
/usr/include/openssl/asn1.h
/usr/include/openssl/asn1_mac.h
/usr/include/openssl/asn1t.h
/usr/include/openssl/bio.h
/usr/include/openssl/blowfish.h
/usr/include/openssl/bn.h
/usr/include/openssl/buffer.h
/usr/include/openssl/camellia.h
/usr/include/openssl/cast.h
/usr/include/openssl/cmac.h
/usr/include/openssl/cms.h
/usr/include/openssl/comp.h
/usr/include/openssl/conf.h
/usr/include/openssl/conf_api.h
/usr/include/openssl/crypto.h
/usr/include/openssl/des.h
/usr/include/openssl/des_old.h
/usr/include/openssl/dh.h
/usr/include/openssl/dsa.h
/usr/include/openssl/dso.h
/usr/include/openssl/dtls1.h
/usr/include/openssl/e_os2.h
/usr/include/openssl/ebcdic.h
/usr/include/openssl/ec.h
/usr/include/openssl/ecdh.h
/usr/include/openssl/ecdsa.h
/usr/include/openssl/engine.h
/usr/include/openssl/err.h
/usr/include/openssl/evp.h
/usr/include/openssl/fips.h
/usr/include/openssl/fips_rand.h
/usr/include/openssl/hmac.h
/usr/include/openssl/idea.h
/usr/include/openssl/krb5_asn.h
/usr/include/openssl/kssl.h
/usr/include/openssl/lhash.h
/usr/include/openssl/md2.h
/usr/include/openssl/md4.h
/usr/include/openssl/md5.h
/usr/include/openssl/modes.h
/usr/include/openssl/obj_mac.h
/usr/include/openssl/objects.h
/usr/include/openssl/ocsp.h
/usr/include/openssl/opensslconf-x86_64.h
/usr/include/openssl/opensslconf.h
/usr/include/openssl/opensslv.h
/usr/include/openssl/ossl_typ.h
/usr/include/openssl/pem.h
/usr/include/openssl/pem2.h
/usr/include/openssl/pkcs12.h
/usr/include/openssl/pkcs7.h
/usr/include/openssl/pqueue.h
/usr/include/openssl/rand.h
/usr/include/openssl/rc2.h
/usr/include/openssl/rc4.h
/usr/include/openssl/ripemd.h
/usr/include/openssl/rsa.h
/usr/include/openssl/safestack.h
/usr/include/openssl/seed.h
/usr/include/openssl/sha.h
/usr/include/openssl/srtp.h
/usr/include/openssl/ssl.h
/usr/include/openssl/ssl2.h
/usr/include/openssl/ssl23.h
/usr/include/openssl/ssl3.h
/usr/include/openssl/stack.h
/usr/include/openssl/symhacks.h
/usr/include/openssl/tls1.h
/usr/include/openssl/ts.h
/usr/include/openssl/txt_db.h
/usr/include/openssl/ui.h
/usr/include/openssl/ui_compat.h
/usr/include/openssl/whrlpool.h
/usr/include/openssl/x509.h
/usr/include/openssl/x509_vfy.h
/usr/include/openssl/x509v3.h
/usr/lib64/libcrypto.so
/usr/lib64/libssl.so
/usr/lib64/pkgconfig/libcrypto.pc
/usr/lib64/pkgconfig/libssl.pc
/usr/lib64/pkgconfig/openssl.pc