- low-level safe version of lizard_decompress() put into an extra source file

- low-level safe version of lizard_decompress() put into an extra source file

- use M_PRIVATE instead of M_SHARED
- use PROT_NONE instead of PROT_READ and only set/clear it for one page
  before/after the operation instead of doing it for all the array
- errno is set instead of returning different negative values
- use longjmp in the signal handler instead of die() and return -1
- use macro ALIGN()