re PR other/43838 (Incorrect output from abi::__cxa_demangle)
PR other/43838
* cp-demangle.c (struct d_print_info): Add flush_count field.
(d_print_init): Initialize it to 0.
(d_print_flush): Increment it.
(d_print_comp): If needed flush before appending ", ". Only
decrement dpi->len if no flushes happened during the recursive
call.
* testsuite/demangle-expected: Add a test for this.