riscv : modify Makefile and add a RISCV_VECT to print log info (#9442)

- Added ggml_cpu_has_riscv_v() in GGML to print system info in log
- Modified Makefile to only use flag when cross compiling for RISC-V

src/llama.cpp

@@ -20672,6 +20672,7 @@ const char * llama_print_system_info(void) {
     s += "ARM_FMA = "     + std::to_string(ggml_cpu_has_arm_fma())     + " | ";
     s += "F16C = "        + std::to_string(ggml_cpu_has_f16c())        + " | ";
     s += "FP16_VA = "     + std::to_string(ggml_cpu_has_fp16_va())     + " | ";
+    s += "RISCV_VECT = "  + std::to_string(ggml_cpu_has_riscv_v())     + " | ";
     s += "WASM_SIMD = "   + std::to_string(ggml_cpu_has_wasm_simd())   + " | ";
     s += "BLAS = "        + std::to_string(ggml_cpu_has_blas())        + " | ";
     s += "SSE3 = "        + std::to_string(ggml_cpu_has_sse3())        + " | ";