make gimme consistently U8

The value of gimme stored in the context stack is U8.
Make all other uses in the main core consistent with this.

My primary motivation on this was that the new function cx_pushblock(),
which I gave a 'U8 gimme' parameter, was generating warnings where callers
were passing I32 gimme vars to it. Rather than play whack-a-mole, it
seemed simpler to just uniformly use U8 everywhere.

Porting/bench.pl shows a consistent reduction of about 2 instructions on
the loop and sub benchmarks, so this change isn't harming performance.

1 files changed, 1 insertions, 1 deletions

diff --git a/pp_pack.c b/pp_pack.c
index 044ea7f2ce..f6964c3f30 100644
--- a/pp_pack.c
+++ b/pp_pack.c
@@ -1826,7 +1826,7 @@ PP(pp_unpack)
 {
     dSP;
     dPOPPOPssrl;
-    I32 gimme = GIMME_V;
+    U8 gimme = GIMME_V;
     STRLEN llen;
     STRLEN rlen;
     const char *pat = SvPV_const(left,  llen);