[v1.05][ARM] Preeliminary support for SVE detection (#259)

src/arm/sve.c

@@ -0,0 +1,15 @@
+#include <stdint.h>
+#include "../common/global.h"
+
+// https://learn.arm.com/learning-paths/servers-and-cloud-computing/sve/sve_basics/#:~:text=Using%20a%20text%20editor%20of%20your%20choice%2C%20copy,svcntb%28%29%29%3B%20%7D%20This%20program%20prints%20the%20vector%20length
+uint64_t sve_cntb(void) {
+  #ifdef __ARM_FEATURE_SVE
+    uint64_t x0 = 0;
+    __asm volatile("cntb %0"
+         : "=r"(x0));
+    return x0;
+  #else
+    printWarn("sve_cntb: Hardware supports SVE, but it was not enabled by the compiler");
+    return 0;
+  #endif
+}