Fix the RX assembler so that it can handle escaped double quote characters, ie: \"
PR 22737
* config/tc-rx.c (rx_start_line): Handle escaped double-quote character.
* testsuite/gas/rx/pr22737.s: New test.
* testsuite/gas/rx/pr22737.d: Likewise.
* testsuite/gas/rx/rx.exp: Run the new test.