GN: Fix Windows tool("asm") for x86-64

build/toolchain/win/BUILD.gn

Index: build/toolchain/win/BUILD.gn
diff --git a/build/toolchain/win/BUILD.gn b/build/toolchain/win/BUILD.gn
index 27b97ad9755179d009db59f5d2d1cd8be51730b1..4b550525712c3aadc8510cc327c76da692e387e5 100644
--- a/build/toolchain/win/BUILD.gn
+++ b/build/toolchain/win/BUILD.gn
@@ -121,7 +121,12 @@ template("msvc_toolchain") {
     }
 
     tool("asm") {
-      command = "$python_path gyp-win-tool asm-wrapper $env ml.exe {{defines}} {{include_dirs}} {{asmflags}} /c /Fo{{output}} {{source}}"
+      if (current_cpu == "x64") {
+        ml = "ml64.exe"
+      } else {
+        ml = "ml.exe"
+      }
+      command = "$python_path gyp-win-tool asm-wrapper $env $ml {{defines}} {{include_dirs}} {{asmflags}} /c /Fo{{output}} {{source}}"
       description = "ASM {{output}}"
       outputs = [
         "{{target_out_dir}}/{{target_output_name}}/{{source_name_part}}.obj",