[riscv64] Fix cross build failed for riscv64.

  When buid with "is_component_build=true" will failed.
  Add lib atomic into lib in v8_libplatform.
  Move func body into cc file

Bug: v8:11975
Change-Id: Ifb844a82360310aba444504f7012fa0c543a49e9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3046980
Auto-Submit: Yahan Lu <yahan@iscas.ac.cn>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Brice Dobry <brice.dobry@futurewei.com>
Reviewed-by: Ji Qiu <qiuji@iscas.ac.cn>
Commit-Queue: Brice Dobry <brice.dobry@futurewei.com>
Cr-Commit-Position: refs/heads/master@{#75919}

BUILD.gn

@@ -552,6 +552,10 @@ config("internal_config") {
   if (is_component_build) {
     defines += [ "BUILDING_V8_SHARED" ]
   }
+
+  if (v8_current_cpu == "riscv64") {
+    libs = [ "atomic" ]
+  }
 }
 
 # Should be applied to all targets that write trace events.
@@ -620,6 +624,10 @@ config("external_config") {
   if (is_component_build) {
     defines += [ "USING_V8_SHARED" ]
   }
+
+  if(current_cpu == "riscv64") {
+    libs = [ "atomic"]
+  }
 }
 
 # This config should only be applied to code that needs to be explicitly
@@ -4960,6 +4968,10 @@ v8_component("v8_libplatform") {
       sources += [ "src/libplatform/tracing/recorder-win.cc" ]
     }
   }
+
+  if (v8_current_cpu == "riscv64") {
+    libs = [ "atomic" ]
+  }
 }
 
 v8_source_set("fuzzer_support") {

src/codegen/riscv64/assembler-riscv64.cc

@@ -227,6 +227,9 @@ Assembler::Assembler(const AssemblerOptions& options,
   block_buffer_growth_ = false;
 }
 
+void Assembler::AbortedCodeGeneration() { constpool_.Clear(); }
+Assembler::~Assembler() { CHECK(constpool_.IsEmpty()); }
+
 void Assembler::GetCode(Isolate* isolate, CodeDesc* desc,
                         SafepointTableBuilder* safepoint_table_builder,
                         int handler_table_offset) {

src/codegen/riscv64/assembler-riscv64.h

@@ -158,9 +158,8 @@ class V8_EXPORT_PRIVATE Assembler : public AssemblerBase {
   explicit Assembler(const AssemblerOptions&,
                      std::unique_ptr<AssemblerBuffer> = {});
 
-  virtual ~Assembler() { CHECK(constpool_.IsEmpty()); }
-
-  void AbortedCodeGeneration() { constpool_.Clear(); }
+  virtual ~Assembler();
+  void AbortedCodeGeneration();
   // GetCode emits any pending (non-emitted) code and fills the descriptor desc.
   static constexpr int kNoHandlerTable = 0;
   static constexpr SafepointTableBuilder* kNoSafepointTable = nullptr;