i386 memory fence incompatible with valgrind

[Matthias Urlichs]

valgrind does this on i386:
      #define ECB_MEMORY_FENCE         __asm__ __volatile__ ("lock; orb
$0, -1(%%esp)" : : : "memory")

This code triggers a warning whenever it is executed under valgrind:
whatever is below the stack pointer is undefined memory by definition.
Not a good idea, as this causes legitimate warnings to get lost in the
noise. :-(

Please access a legitimate memory location instead.

-- 
-- Matthias Urlichs