uClibc issues

[smx-smx]

On uClibc, we must load libdl.so ourselves by using parts from ldso

The code that does so is an adaptation of the code from the uClibc source code, but it's a trimmed down version that does the bare minimum to get libdl.so loaded

This has several implications:

• .init/.fini aren't handled, and you will see the following warning on screen
  symbol 'dl_cleanup': can't resolve symbol
• symbol scope handling
  later versions of uClibc introduced a symbol scope for loaded shared libraries.
  the problem with this is that the offset of symbol_scope is not fixed (depends on how uClibc was compiled, see https://github.com/kraj/uClibc/blob/ca1c74d67dd115d059a875150e10b8560a9c35a8/ldso/include/dl-hash.h#L82)
• we need to avoid loading libdl twice
• detect the uClibc version (don't assume MIPS == "old" uClibc). old uClibc doesn't use symbol scopes (making it ironically easier for us)

This ultimately results in the inability to run the injection code more than once on uClibc

[smx-smx]

Added symbol scope detection heuristic in 9e77ceb, to be improved