Conda-forge's build environment on ARM uses sysroot_linux-aarch64 2.17, which
is based on glibc 2.17 so <sys/auxv.h> does not define HWCAP_* values on ARM.
Work around this by including the kernel header to get the desired values.

--- a/simd.c	2024-09-13 07:59:23.644080046 +1200
+++ b/simd.c	2024-09-13 07:59:47.788059051 +1200
@@ -44,6 +44,8 @@
 
 #if defined __linux__ || defined __FreeBSD__
 #include <sys/auxv.h>
+// Ensure ARM HWCAP_* values are defined even on old glibc
+#include <asm/hwcap.h>
 #elif defined __APPLE__
 #include <sys/types.h>
 #include <sys/sysctl.h>
--- a/htscodecs/htscodecs/rANS_static4x16pr.c	2023-10-10 02:54:16
+++ b/htscodecs/htscodecs/rANS_static4x16pr.c	2024-03-06 00:01:14
@@ -1030,6 +1030,8 @@
 
 #if defined(__linux__) || defined(__FreeBSD__)
 #include <sys/auxv.h>
+// Ensure ARM HWCAP_* values are defined even on old glibc
+#include <asm/hwcap.h>
 #elif defined(_WIN32)
 #include <processthreadsapi.h>
 #endif
