Mitigate clang warnings:

Mitigate clang warnings:

gcc/range-op.cc:1752:16: warning: 'wi_fold' overrides a member function but is not marked 'override' [-Winconsistent-missing-override]
gcc/range-op.cc:1757:16: warning: 'wi_op_overflows' overrides a member function but is not marked 'override' [-Winconsistent-missing-override]
gcc/range-op.cc:1759:16: warning: 'op1_range' overrides a member function but is not marked 'override' [-Winconsistent-missing-override]
gcc/range-op.cc:1763:16: warning: 'op2_range' overrides a member function but is not marked 'override' [-Winconsistent-missing-override]
gcc/range-op.cc:1928:16: warning: 'wi_fold' overrides a member function but is not marked 'override' [-Winconsistent-missing-override]
gcc/range-op.cc:1933:16: warning: 'wi_op_overflows' overrides a member function but is not marked 'override' [-Winconsistent-missing-override]

gcc/ChangeLog:

	* range-op.cc: Add final override keywords.