m_debuginfo: Suppress warning about not handling entry_value ops

m_debuginfo: Suppress warning about not handling entry_value ops

The warning: evaluate_Dwarf3_Expr: unhandled DW_OP_ 0xf3 isn't
very helpful. This means we didn't handle DW_OP_GNU_entry_value.

DW_OP_GNU_entry_value (or DWARF5 DW_OP_entry_value) means interpreting
the given DWARF expression using register values as they were upon
entering the function. Which is non-trivial to implement.

We can fail the evaluation of the DWARF expression without warning
about it by default, since it isn't really needed for any current
valgrind functionality (and it is only done with --read-var-info=yes.