hexagon: update to use GGML_BACKEND_API

Author: max-krasnyansky

ggml/include/ggml-hexagon.h

@@ -8,11 +8,11 @@ extern "C" {
 #endif
 
 // backend API
-GGML_API ggml_backend_t ggml_backend_hexagon_init(void);
+GGML_BACKEND_API ggml_backend_t ggml_backend_hexagon_init(void);
 
-GGML_API bool ggml_backend_is_hexagon(ggml_backend_t backend);
+GGML_BACKEND_API bool ggml_backend_is_hexagon(ggml_backend_t backend);
 
-GGML_API ggml_backend_reg_t ggml_backend_hexagon_reg(void);
+GGML_BACKEND_API ggml_backend_reg_t ggml_backend_hexagon_reg(void);
 
 #ifdef  __cplusplus
 }