Remove offer_nice_chunk(), PL_nice_chunk and PL_nice_chunk_size.

These provided a non-public API for the hash and array code to donate free
memory direct to the SV head allocation routines, instead of returning it
to the malloc system with free().

I assume that on some older mallocs this could offer significant benefits.
However, my benchmarking on a modern malloc couldn't detect any significant
effect (positive or negative) on removing the code. Its (continued) presence,
however, has downsides

a: slightly more code complexity
b: slightly larger interpreter structure
c: in the steady state, if net creation of SVs is zero, 1 chunk of allocated
   but unused memory will exist (per thread)

So I think it best to remove it.

1 files changed, 0 insertions, 6 deletions

diff --git a/proto.h b/proto.h
index b915db25f8..a29bdc00cb 100644
--- a/proto.h
+++ b/proto.h
@@ -6691,12 +6691,6 @@ PERL_CALLCONV STRLEN *	Perl_new_warnings_bitfield(pTHX_ STRLEN *buffer, const ch
 	assert(bits)
 
 
-PERL_CALLCONV void	Perl_offer_nice_chunk(pTHX_ void *const chunk, const U32 chunk_size)
-			__attribute__nonnull__(pTHX_1);
-#define PERL_ARGS_ASSERT_OFFER_NICE_CHUNK	\
-	assert(chunk)
-
-
 #ifndef SPRINTF_RETURNS_STRLEN
 PERL_CALLCONV int	Perl_my_sprintf(char *buffer, const char *pat, ...)
 			__attribute__nonnull__(1)