could not staticallly determine size of realloc

[ZuseZ4]

The safe gmm implementation could idiomatically use Box<[T]>, since we know those Vec's wont' change their length. However, Enzyme fails with:

error: <unknown>:0:0: in function preprocess___rdl_realloc ptr (ptr, i64, i64, i64): Enzyme: could not statically determine size of realloc   %23 = tail call noundef ptr @realloc(ptr noundef %0, i64 noundef %3) #119 - because of - ptr %0

working variant is in: https://github.com/EnzymeAD/Enzyme/pull/1797