`GETMATIDXVAR` macro hides function names

[no-lex]

It sounds hard to believe, but using macros to construct function names makes them hard to find. Indeed, since GETMATIDXVAR creates a function name by concatenating arguments, it is impossible to Ctrl-F for a function and find where it is defined. To resolve this, GETMATIDXVAR should be hurled directly into the sun, and replaced with literally anything else.