x86-64, struct callbacks: leave registers if a struct doesn't fit
struct-by-value: don't overwrite when copying values from registers to memory
tests: failing overwrite cases
x86-64, struct-by-value: leave registers if a struct doesn't fit
x86-64, struct-by-value: don't read past input struct
tests: struct-by-value parameter overread
Resolve a loop in constraints
x86-64, struct-by-value: fix record-arg-tn for win32