BUILD: pools: fix backport of no-memory-trimming on non-linux OS

Commit 4bcff9ba4 in 2.5 ("MINOR: pools: add a new global option
"no-memory-trimming"") was missing some extra ifdefs for the cases
where the allocator doesn't have malloc_trim() and fails to build
on windows.

This must be backported to 2.4.

(cherry picked from commit a11c3b83e3a3689700b12551650d8f5a681db5fb)
Signed-off-by: Willy Tarreau <w@1wt.eu>
diff --git a/src/pool.c b/src/pool.c
index 1f116d5..75c67d0 100644
--- a/src/pool.c
+++ b/src/pool.c
@@ -671,6 +671,7 @@
 }
 #endif
 
+#if defined(HA_HAVE_MALLOC_TRIM)
 /* config parser for global "no-memory-trimming" */
 static int mem_parse_global_no_mem_trim(char **args, int section_type, struct proxy *curpx,
                                        const struct proxy *defpx, const char *file, int line,
@@ -681,13 +682,16 @@
 	disable_trim = 1;
 	return 0;
 }
+#endif
 
 /* register global config keywords */
 static struct cfg_kw_list mem_cfg_kws = {ILH, {
 #ifdef DEBUG_FAIL_ALLOC
 	{ CFG_GLOBAL, "tune.fail-alloc", mem_parse_global_fail_alloc },
 #endif
+#if defined(HA_HAVE_MALLOC_TRIM)
 	{ CFG_GLOBAL, "no-memory-trimming", mem_parse_global_no_mem_trim },
+#endif
 	{ 0, NULL, NULL }
 }};