Change the lsx to baseline features.

This patch change lsx to baseline feature, and lasx to dispatch
feature. Additionally, the runtime detection methods for lasx and
lsx have been modified.

modules/core/src/system.cpp

@@ -154,6 +154,12 @@ void* allocSingletonNewBuffer(size_t size) { return malloc(size); }
 # endif
 #endif
 
+#if defined __loongarch64
+#include "sys/auxv.h"
+#define LA_HWCAP_LSX   (1<<4)
+#define LA_HWCAP_LASX  (1<<5)
+#endif
+
 #if defined _WIN32 || defined WINCE
 #ifndef _WIN32_WINNT           // This is needed for the declaration of TryEnterCriticalSection in winbase.h with Visual Studio 2005 (and older?)
   #define _WIN32_WINNT 0x0400  // http://msdn.microsoft.com/en-us/library/ms686857(VS.85).aspx
@@ -704,12 +710,11 @@ struct HWFeatures
         have[CV_CPU_RVV] = true;
     #endif
 
-    #if defined __loongarch_sx
-        have[CV_CPU_LSX] = true;
-    #endif
+    #if defined __loongarch64 && defined __linux__
+        int flag = (int)getauxval(AT_HWCAP);
 
-    #if defined __loongarch_asx
-        have[CV_CPU_LASX] = true;
+        have[CV_CPU_LSX] = (flag & LA_HWCAP_LSX) != 0;
+        have[CV_CPU_LASX] = (flag & LA_HWCAP_LASX) != 0;
     #endif
 
         bool skip_baseline_check = false;