More shared_bram_mask.m fixes

Use get_param instead of eval_param where appropriate.

Make sure the mask init script runs OK even when inside a library or other
block that does not have a System Generator block.
Set MaskSelfModifiable in casper_library_reorder

The dbl_buffer, qdr_transpose, and qdr_ct blocks from casper_library_reorder
did not have "Allow library block to modify its contents" enabled.  This
enables that option on those blocks.
Remove use_rpm from BRAM blocks in xps_library

The "Shared BRAM", "qdr" and "dram" blocks in xps_library contain BRAM blocks
used for simulation only.  These BRAM blocks had a "use_rpm" parameter that was
discontinued in System Generator 14.x.  Having this parameter set caused
annoying but harmless warning messages in 14.x, but since these blocks are only
used for simulation, this parameter has been removed from these blocks in
xps_library to make use with 14.x quieter.