On linux, we have the following dep chain:aws-dsql-auth -> aws-c-http -> aws-c-io -> aws-lcWe only use aws-c-http for request signing, but we cannot make aws-c-ioconditionally required. aws-c-io only works with aws-lc on linux, whichmeans we land up in a situation where we have two libcryptos (postgreswants openssl).Our overall solution is to make fe-dsql-auth.o a self-containedfile (hiding the aws-dsql-auth dep chain) and explicitly exclude thelibs we don't want.

Doesn't handle occ yet

It doesn't work because we end up with a few unnamed syms.

This commit wires up the aws-c-common logging infra. You can log tostd{out,err} or a file, and set the level through env vars. The readmehas examples.With this logging I realized that imds wasn't working due to a missinghttp client. That's been fixed now.