Remove get_stack_bang_address because it's a workaround to make JVM signal handler work correctly on Linux with kernel below 2.6.6.

Such a kernel version (< 2.6.6) is quite old and not well supported anymore by various distros hence we can consider that that kernel bug is gone on more recently JDK version, i.e. version above 13.

Removing get_stack_bang_address simplifies the signal handler code on Linux / PPC64 so we don't have do discern between data and instruction storage interruption.