Suppress output from the dwp tool in link scripts.

- The output doesn't seem useful. When data is missing the tool
segfaults rather than printing a message.

Bug: 1122182
Change-Id: I46842793e831b02d169f8d3acc4fa82de3f77951
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2521846
Commit-Queue: Nelson Billing <nbilling@google.com>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824913}

build/extract_partition.py

@@ -52,7 +52,9 @@ def main():
         args.dwp, '-e', args.unstripped_output, '-o',
         args.unstripped_output + '.dwp'
     ]
-    subprocess.check_call(dwp_args)
+    # Suppress output here because it doesn't seem to be useful. The most
+    # common error is a segfault, which will happen if files are missing.
+    subprocess.check_output(dwp_args, stderr=subprocess.STDOUT)
 
 
 if __name__ == '__main__':

build/toolchain/gcc_link_wrapper.py

@@ -68,15 +68,18 @@ def main():
     exe_file = args.output
     if args.unstripped_file:
       exe_file = args.unstripped_file
-    dwp_proc = subprocess.Popen(
-        wrapper_utils.CommandToRun(
-            [args.dwp, '-e', exe_file, '-o', exe_file + '.dwp']))
+    # Suppress output here because it doesn't seem to be useful. The most
+    # common error is a segfault, which will happen if files are missing.
+    with open(os.devnull, "w") as devnull:
+      dwp_proc = subprocess.Popen(wrapper_utils.CommandToRun(
+          [args.dwp, '-e', exe_file, '-o', exe_file + '.dwp']),
+                                  stdout=devnull,
+                                  stderr=subprocess.STDOUT)
 
   # Finally, strip the linked executable (if desired).
   if args.strip:
-    result = subprocess.call(CommandToRun([
-        args.strip, '-o', args.output, args.unstripped_file
-        ]))
+    result = subprocess.call(
+        CommandToRun([args.strip, '-o', args.output, args.unstripped_file]))
 
   if dwp_proc:
     dwp_result = dwp_proc.wait()

build/toolchain/gcc_solink_wrapper.py

@@ -164,9 +164,13 @@ def main():
   # If dwp is set, then package debug info for this SO.
   dwp_proc = None
   if args.dwp:
-    dwp_proc = subprocess.Popen(
-        wrapper_utils.CommandToRun(
-            [args.dwp, '-e', args.sofile, '-o', args.sofile + '.dwp']))
+    # Suppress output here because it doesn't seem to be useful. The most
+    # common error is a segfault, which will happen if files are missing.
+    with open(os.devnull, "w") as devnull:
+      dwp_proc = subprocess.Popen(wrapper_utils.CommandToRun(
+          [args.dwp, '-e', args.sofile, '-o', args.sofile + '.dwp']),
+                                  stdout=devnull,
+                                  stderr=subprocess.STDOUT)
 
   # Next, generate the contents of the TOC file.
   result, toc = CollectTOC(args)