Merge pull request #2 from k15tfu/fix-build-aarch64

Use cntvct_el0 to get time in utf_converters/performance test case on ARM64

Author: ww898

test/utf_converters_test.cpp

@@ -565,6 +565,12 @@ uint64_t get_time() throw()
 #endif
         );
     return static_cast<uint64_t>(hi) << 32 | lo;
+#elif defined(__aarch64__)
+    uint64_t cntvct_el0;
+    asm volatile(
+        "mrs %0, cntvct_el0\n\t"
+        : "=r" (cntvct_el0) : : );
+    return cntvct_el0;
 #else
 #error Unsupported architecture
 #endif