Use statically linked stdlib

[javierbrk]

This pull request implements statically linked version of shared-state-async to help reduce this issue libremesh/lime-packages#1191

[javierbrk]

The changes proposed here need more testing, so far it has only been tested in x86_64 system.
This new build now uses 290K bin/packages/x86_64/libremesh/shared-state-async_~use-sta-r1_x86_64.ipk but it does not depend on stdlibcpp any more.

[javierbrk]

This build has been tested and the compilation succeeds.
The statically built binary has been used in montenet for more than 8 days in a row and the binary works as expected.
This pull is ready to be merged.