Downgrade libpcre for x86

The new version breaks git, but only once it's in the repository.
Installing it manually alongside the old one works. Rebuilding git and
uploading a new package does not work, as for the package management,
the new version is exactly equal to the old, as the port revision isn't
newer. We need to come up with a proper way to handle this.

Also removes zsh, as that requires the new libpcre.
kernel/arm: implement stubs for new functions

These were mostly introduced after the scheduler merge.
arm/atomic: fixup arch_atomic.h

* Remove _inline functions, since we're not using inlines
* Use compiler barrier instead of GCC builtin
arm: fix compiler ARM architecture detection

For determining if to define ATOMIC{,64}_FUNCS_ARE_SYSCALLS, use
the proper macro.
board/arm: cleanup setting of ARM compiler options

The ones with ARCH extension are used for setting up the KERNEL
ones, so no need to try and set both.
Also, the verdex target was not setting the ARCH one, and therefore
never configured gcc for ARMv5.
arm/atomic: round of atomic function changes

* change vint{32,64} to int{32,64} in:
  * kernel implementation
  * syscall definitions
  * libroot prototypes
* update syscall functions with new atomic prototypes.