Revert "Fix autolink mechanism for static libraries on Linux"

[drexin]

Reverts #2996

The icui18n library that is linked against is not necessarily the same as the one used to build Foundation and Swift, so this is causing builds to fail.

[drexin]

cc: @kateinoigakukun

[drexin]

@swift-ci test

[millenomi]

@swift-ci please test and merge

[kateinoigakukun]

@drexin Could you let me know a sample failed CI job for investigation?

[drexin]

@kateinoigakukun https://ci.swift.org/job/oss-swift-package-centos-7/1112

/opt/rh/devtoolset-7/root/usr/lib/gcc/x86_64-redhat-linux/7/../../../../bin/ld.gold: error: cannot find -licui18n
clang-5.0: error: linker command failed with exit code 1 (use -v to see invocation)
<unknown>:0: error: link command failed with exit code 1 (use -v to see invocation)

[drexin]

If we are building ICU from source, it should link against those libraries, which may have a different name (e.g. icui18nswift in case of the default Linux build). So the correct solution I think would be to determine to actual name of the library that cmake detects and use that here as well.

[kateinoigakukun]

Thank you for sharing :) Oh, I forgot swift suffix variants. I'll work on this in a few days