Make sure to clear InflatedHeader when it's not used
Fix a C/C++ undefined behavior case for bit shifting

The old version bit shifted 63 bits, which overflows an unsigned long on
64 bit systems (it would shift 31 bits on a 32 bit system). This changes
the algorithm to not depend on this behavior.

Caught with the Clang Static Analyzer: http://clang-analyzer.llvm.org
Remove unused Rubinius::VariableScope.synthesize
Fix warnings exposed by clang static analyzer

Some patterns here are realloc() being able to fail and having to free()
the original data after a failed realloc, and reading potentially NULL
values.
Remove unused definition

This header file already loads config.h which defines NORETURN. So this
definition was never used.