verify_ssa failure in ACATS test

[Richard Kenner]

This looks to be the only one that still remains:

cxaa010.adb: In function 'CXAA010':
cxaa010.adb:78: error: Expected an SSA_NAME object
while verifying SSA_NAME tc_id in statement
#   tc_id = V_MAY_DEF <tc_id>;
#   VUSE <neighborhood_taxes_853>;
tc_id = *ruatmp.255_8129;