[GN]: Add asmflags

tools/gn/substitution_type.cc

Index: tools/gn/substitution_type.cc
diff --git a/tools/gn/substitution_type.cc b/tools/gn/substitution_type.cc
index 2713ee2daf4abdeabc13be42afb2bb5f37b3a642..f67df262a21e80c6e39a41cdb3ae3f48c22a01f3 100644
--- a/tools/gn/substitution_type.cc
+++ b/tools/gn/substitution_type.cc
@@ -28,6 +28,7 @@ const char* kSubstitutionNames[SUBSTITUTION_NUM_TYPES] = {
   "{{target_out_dir}}",  // SUBSTITUTION_TARGET_OUT_DIR
   "{{target_output_name}}",  // SUBSTITUTION_TARGET_OUTPUT_NAME
 
+  "{{asmflags}}",  // SUBSTITUTION_ASMFLAGS
   "{{cflags}}",  // SUBSTITUTION_CFLAGS
   "{{cflags_c}}",  // SUBSTITUTION_CFLAGS_C
   "{{cflags_cc}}",  // SUBSTITUTION_CFLAGS_CC
@@ -64,6 +65,7 @@ const char* kSubstitutionNinjaNames[SUBSTITUTION_NUM_TYPES] = {
     "target_out_dir",      // SUBSTITUTION_TARGET_OUT_DIR
     "target_output_name",  // SUBSTITUTION_TARGET_OUTPUT_NAME
 
+    "asmflags",      // SUBSTITUTION_ASMFLAGS
     "cflags",        // SUBSTITUTION_CFLAGS
     "cflags_c",      // SUBSTITUTION_CFLAGS_C
     "cflags_cc",     // SUBSTITUTION_CFLAGS_CC
@@ -133,6 +135,7 @@ bool IsValidCompilerSubstitution(SubstitutionType type) {
   return IsValidToolSubstutition(type) ||
          IsValidSourceSubstitution(type) ||
          type == SUBSTITUTION_SOURCE ||
+         type == SUBSTITUTION_ASMFLAGS ||
          type == SUBSTITUTION_CFLAGS ||
          type == SUBSTITUTION_CFLAGS_C ||
          type == SUBSTITUTION_CFLAGS_CC ||