The test was checking for two `ptr` arguments by matching commas (or
non-commas), however after
https://github.com/llvm/llvm-project/pull/117104 LLVM adds an
`initializes((0, 16))` attribute, which includes a comma.
So instead, we make the test check for two LLVM values, i.e. something
prefixed by %.
(See also https://crbug.com/380707238)