- Implement NEON runtime detection on FreeBSD 11.* armv6

--- src/platform.c.orig	2019-08-16 20:55:07 UTC
+++ src/platform.c
@@ -41,8 +41,36 @@
 #include <asm/hwcap.h>
 #include <sys/auxv.h>
 #elif defined(__FreeBSD__) && defined(__arm__)
+#if __FreeBSD__ >= 12
 #include <sys/auxv.h>
+#else
+#include <sys/param.h>
+#include <sys/sysctl.h>
+#include <elf.h>
+#include <errno.h>
+#include <unistd.h>
+
+static unsigned long getauxval(unsigned long type) {
+  Elf_Auxinfo auxv[AT_COUNT];
+  size_t len = sizeof(auxv);
+  int mib[] = {
+    CTL_KERN,
+    KERN_PROC,
+    KERN_PROC_AUXV,
+    getpid(),
+  };
+
+  if (sysctl(mib, nitems(mib), auxv, &len, NULL, 0) != -1) {
+    for (size_t i = 0; i < nitems(auxv); i++)
+      if ((unsigned long)auxv[i].a_type == type)
+        return auxv[i].a_un.a_val;
+
+    errno = ENOENT;
+  }
+  return 0;
+}
 #endif
+#endif
 
 #if defined(__linux__)
 /* memfd_create was introduced in glibc 2.27 */
@@ -82,9 +110,13 @@ bool neon_available(void)
 #if defined(__linux__) && defined(__arm__)
 	return (getauxval(AT_HWCAP) & HWCAP_NEON) != 0;
 #elif defined(__FreeBSD__) && defined(__arm__)
+#if __FreeBSD__ < 12
+	return (getauxval(AT_HWCAP) & HWCAP_NEON) != 0;
+#else
 	unsigned long hwcap = 0;
 	elf_aux_info(AT_HWCAP, &hwcap, sizeof(hwcap));
 	return (hwcap & HWCAP_NEON) != 0;
+#endif
 #endif
 	return true;
 }