If not compiling with -march=iwmmxt, the configure test will still pass,
thinking that the __builtin_arm_* intrinsic is a function instead of
generating a single instruction. Since no linking is done, the configure
test doesn't catch this, and we get linking errors in the build.
#ifndef __arm__
#error "IWMMXT is only available on ARM"
#endif
#ifndef __arm__
#error "IWMMXT is only available on ARM"
#endif
+#ifndef __IWMMXT__
+#error "IWMMXT not enabled (with -march=iwmmxt)"
+#endif
#if defined(__GNUC__) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 5))
#error "Need GCC >= 4.5 for IWMMXT intrinsics"
#endif
#if defined(__GNUC__) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 5))
#error "Need GCC >= 4.5 for IWMMXT intrinsics"
#endif