Drop jumbo support for .S asm files

We don't need it and it doesn't work. It's probably been ok up
until now because we have never had more than one S file per
build target.

See errors at
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Jumbo%20Win%20x64/22538

R=fs@opera.com

Change-Id: Idde99aba83e01c0111e5a50590e319993e0effaa
Reviewed-on: https://chromium-review.googlesource.com/c/1340312
Commit-Queue: Daniel Bratell <bratell@opera.com>
Reviewed-by: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#608826}

build/config/jumbo.gni

@@ -120,7 +120,6 @@ template("internal_jumbo_target") {
     }
     has_c_file = false
     has_objective_c_file = false
-    has_S_file = false
     sources_in_jumbo_files = []
     assert(merge_limit > 0)
     foreach(source_file, invoker_sources) {
@@ -130,8 +129,6 @@ template("internal_jumbo_target") {
         has_c_file = true
       } else if (source_ext == "mm") {
         has_objective_c_file = true
-      } else if (source_ext == "S") {
-        has_S_file = true
       } else if (source_ext == "cc" || source_ext == "cpp") {
         if (current_file_index == next_chunk_start) {
           jumbo_files += [ "$gen_target_dir/" + target_name + "_jumbo_" +
@@ -166,9 +163,6 @@ template("internal_jumbo_target") {
     if (has_objective_c_file) {
       jumbo_files += [ "$gen_target_dir/" + target_name + "_jumbo_mm.mm" ]
     }
-    if (has_S_file) {
-      jumbo_files += [ "$gen_target_dir/" + target_name + "_jumbo_S.S" ]
-    }
   }
 
   if (use_jumbo_build_for_target) {

build/config/merge_for_jumbo.py

@@ -119,7 +119,7 @@ def main():
 
   written_output_set = set()  # Just for double checking
   written_input_set = set()  # Just for double checking
-  for language_ext in (".cc", ".c", ".mm", ".S"):
+  for language_ext in (".cc", ".c", ".mm",):
     if language_ext == ".cc":
       ext_pattern = (".cc", ".cpp")
     else: