AWS SDK Build Errors

Thanks @ihnorton.

I just pulled the latest dev branch, recreated the build folder, executed:

../bootstrap --enable-s3 --enable-static-tiledb --prefix=/usr/local

and built using make from within an Amazon Linux 2 VM.

The overall build failed at the point of building libcurl, with the following entry in the externals/src/ep/ep_curl-stamp/ep_curl-build-err.log file:

vtls/openssl.c: In function "Curl_ossl_seed":
vtls/openssl.c:428:15: error: implicit declaration of function "RAND_egd"; did you mean "RAND_add"? [-Werror=implicit-function-declaration]
    int ret = RAND_egd(data->set.str[STRING_SSL_EGDSOCKET]?
              ^~~~~~~~
              RAND_add
cc1: some warnings treated as errors
make[5]: *** [vtls/libcurl_la-openssl.lo] Error 1
make[4]: *** [all] Error 2
make[3]: *** [all-recursive] Error 1

I can see you are already dealing with build issues here, so I will keep an eye on that issue.