ELF file symbols sealer.

Theory of operations.

When statically linking with libstdc++ we could encounter rather nasty side effects coming from ODR and conflicts with system libstdc++.so. So to make library fully "sealed" we introduce a tool which modifies all symbols but having certain prefix to be hidden by default and thus not interferring with system libstc++.

Actual selection of how to hide symbol may vary, and the least intrustive way seems to set ELF symbol's st_other field to STV_PROTECTED (see https://sources.debian.org/src/glibc/2.19-18+deb8u9/elf/dl-lookup.c/#L788 for additional info). If required, more aggressive mechanisms, such as complete symbol rename is possible.