[gm.py] Strip carriage returns from mksnapshot arguments

Change-Id: I25a2299e5e261cc125c7ff0e1acdeddbd7f664ff
Reviewed-on: https://chromium-review.googlesource.com/c/1475753Reviewed-by: Dan Elphick <delphick@chromium.org>
Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
Cr-Commit-Position: refs/heads/master@{#59659}

tools/dev/gm.py

@@ -281,8 +281,8 @@ class Config(object):
       match = csa_trap.search(output)
       extra_opt = match.group(1) if match else ""
       cmdline = re.compile("python ../../tools/run.py ./mksnapshot (.*)")
-      match = cmdline.search(output)
-      cmdline = PrepareMksnapshotCmdline(match.group(1), path) + extra_opt
+      orig_cmdline = cmdline.search(output).group(1).strip()
+      cmdline = PrepareMksnapshotCmdline(orig_cmdline, path) + extra_opt
       _Notify("V8 build requires your attention",
               "Detected mksnapshot failure, re-running in GDB...")
       _Call(cmdline)