Due to an accident, we export __longjmp under a public symbol version
for the powerpc32/fpu configuration.
__longjmp is declared as hidden for internal use. This means that any
reference to this symbol (of which there aren't any right now in
libc.so) will cause the symbol to turn unexported. The reason is that
the linker does not distinguish between hidden definitions and
references. GCC emits a .hidden directive in the __longjmp-referencing
translation unit, and this kills the .symver-based export.
I propose the removal of the __longjmp export as the simplest fix.
__longjmp is in the implementation namespace and is not used in a public
header. As a result, nothing out there should reference it.
If this is not acceptable, I'll come up with different approach to
address this. But I prefer to address this issue in this way.
Tested on a powerpc32/fpu configuration with no regressions.