bash: Update to version 5.1.8 plus patches 9 to 12

bash: Update to version 5.1.8 plus patches 9 to 12

- Update main file from 5.1 to 5.1.8 (includes patches 1 to 8)
- Remove patches 1 to 4
- Changelog - Patches 1 to 4 from the previous IPFire version together with patches 5 to
     8 are now included into bash-5.1.8 followed by application of patches 9 to 12
   Patch 12
    There is a possible race condition that arises when a child process receives
     a signal trapped by the parent before it can reset the signal dispositions.
     The child process is not supposed to trap the signal in this circumstance.
   Patch 11
    When reading a compound assignment, and running it through the parser to
     split it into words, we need to save and restore any alias we're currently
     expanding.
   Patch 10
    If `wait -n' is interrupted by a trapped signal other than SIGINT, it does
     not completely clean up state, and that can prevent subsequent calls to
     `wait -n' from working correctly.
   Patch 9
    The bash malloc implementation of malloc_usable_size() does not follow the
     specification. This can cause library functions that use it to overwrite
     memory bounds checking.
   Patch 8
    Process substitution FIFOs opened by child processes as targets of redirections
     were not removed appropriately, leaving remnants in the file system.
   Patch 7
    The code to check readline versions in an inputrc file had the sense of the
     comparisons reversed.
   Patch 6
    Make sure child processes forked to run command substitutions are in the
     proper process group.
   Patch 5
    Fix two memory leaks when assigning arrays using compound assignment syntax.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Acked-by: Peter Müller <peter.mueller@ipfire.org>