Checking mallopt() during configure.

mallopt() is absent on Alpine musl.

auto/malloc

@@ -157,3 +157,19 @@ if [ $nxt_found = no ]; then
                       }"
     . auto/feature
 fi
+
+
+# Linux mallopt().
+
+nxt_feature="Linux mallopt()"
+nxt_feature_name=NXT_HAVE_MALLOPT
+nxt_feature_run=
+nxt_feature_incs=
+nxt_feature_libs=
+nxt_feature_test="#include <malloc.h>
+
+                  int main() {
+                      mallopt(M_PERTURB, 0x55);
+                      return 0;
+                  }"
+. auto/feature

src/nxt_lib.c

@@ -48,7 +48,7 @@ nxt_lib_start(const char *app, char **argv, char ***envp)
 
     nxt_main_log.level = NXT_LOG_DEBUG;
 
-#if (NXT_LINUX)
+#if (NXT_HAVE_MALLOPT)
     /* Fill memory with 0xAA after malloc() and with 0x55 before free(). */
     mallopt(M_PERTURB, 0x55);
 #endif