update to clang-12

Signed-off-by: Nchenhao <chenhao346@huawei.com>

musl_config.gni

@@ -28,7 +28,7 @@ declare_args() {
 
 declare_args() {
   runtime_lib_path =
-      "//prebuilts/clang/ohos/linux-x86_64/llvm/lib/clang/10.0.1/lib"
+      "//prebuilts/clang/ohos/linux-x86_64/llvm/lib/clang/12.0.1/lib"
   user_custom_libc = true
   musl_ported_dir = "intermidiates/${musl_target_os}/musl_src_ported"
   musl_inc_out_dir = "usr/include/${musl_target_triple}"