all: replace C.int with i32

[kbkpbot]

v fmt -new_int -w .

This will convert all C.xx(xx int) int to C.xx(xx i32) i32
As int will be platform depend, i32 or i64.

related to PR #25298, #25236

BTW: I think we can fix checker to issue a notice about use int in C function declaration.

[JalonSolov]

Not sure this is a good idea. According to C specs, the size of int and all other integer types are implementation defined. The only guarantee is that int will be at least large enough to handle i16 range of values.

On some C compilers (mostly older ones), int == i16. On most modern compilers, int == i32, but on some, int == i32 for 32-bit targets, and int == i64 on 64-bit targets.