refactor: the long goodbye

long is 32 bits on windows, while it is 64 bits on other architectures.
This makes the type suboptimal for a codebase meant to be
cross-platform. Replace it with more appropriate integer types.

src/nvim/match.c

@@ -419,7 +419,7 @@ static void next_search_hl(win_T *win, match_T *search_hl, match_T *shl, linenr_
   FUNC_ATTR_NONNULL_ARG(2)
 {
   colnr_T matchcol;
-  long nmatched = 0;
+  int nmatched = 0;
   const int called_emsg_before = called_emsg;
 
   // for :{range}s/pat only highlight inside the range