Bug 723937 - Slapi_Counter API broken on  32-bit F15
    
    We use some embedded assembly code to implement atomic 64-bit
    counter operations on 32-bit platforms.  On F15, gcc optimizes
    this assembly code, breaking our counter get/set functions.  It
    turns out that we can just use the gcc built-in atomic operation
    functions now (this wasn't the case in the past).
    
    This patch removes our get/set assembly code and just uses the
    gcc built-in functions instead.