BaseTools: Fix Segmentation fault: 11 when build AppPkg with XCODE5
    
    it is a bug in mtoc setting the size of the debug directory entry to
    the size of the .debug section, not the size of the
    EFI_IMAGE_DEBUG_DIRECTORY_ENTRY. It was causing a loop to iterate and
    get bogus EFI_IMAGE_DEBUG_DIRECTORY_ENTRY data and pass that to
    memset() and boom.
    
    Cc: Liming Gao <liming.gao@intel.com>
    Cc: Michael D Kinney <michael.d.kinney@intel.com>
    Contributed-under: TianoCore Contribution Agreement 1.1
    Signed-off-by: Andrew Fish <afish@apple.com>
    Reviewed-by: Liming Gao <liming.gao@intel.com>