*
NAME
    AttemptLockLayerRom -- Attempt to Lock layer structure
                                     by rom(gfx lib) code

SYNOPSIS
    gotit = AttemptLockLayerRom( layer )
     d0                           a5

    BOOL AttempLockLayerRom( struct layer * );

FUNCTION
    Query the current state of the lock on this layer. if it is
    already locked then return FALSE, could not lock. If the
    layer was not locked then lock it and return true.
    This call does not destroy any registers.
    This call nests so that callers in this chain will not lock
    themselves out.

INPUTS
    layer - pointer to layer structure

RESULT
    gotit - TRUE or FALSE depending on whether the layer was
            successfully locked by the caller.

SEE ALSO
    locklayerrom() unlocklayerrom()