Dynamic library loader: search in -L directories before default ones

[HertzDevil]

Fixes #12214.

The link flags for OpenSSL and libcrypto already include the explicit directory returned by pkg-config, because at one point we wanted to detect OpenSSL 1.0.2 and enable its new features if found. The problem is that our loader always tries the default library paths before ones specified via the -Ls from the link flags, and the first entry is /usr/lib, which means the system libraries are always searched first, and /usr/lib/libcrypto.dylib is specifically made to abort any application that attempts to load it.

That failure also happens with a plain dlopen, by the way:

LibC.dlopen("/usr/lib/libcrypto.dylib", LibC::RTLD_LAZY | LibC::RTLD_GLOBAL)
LibC.dlopen("libcrypto.dylib", LibC::RTLD_LAZY | LibC::RTLD_GLOBAL)

The MSVC loader already searches in the directories specified via /LIBPATH before the default ones.