Rollup merge of #151571 - androm3da:bcain/cstr_merge, r=tgross35

Fix cstring-merging test for Hexagon target

Hexagon assembler uses `.string` directive instead of `.asciz` for null-terminated strings. Both are equivalent but the test was only checking for `.asciz`.

Update the CHECK patterns to accept both directives using `.{{asciz|string}}` regex pattern.

Author: matthiaskrgr