disable regen.sh due to possible build races

It looks like sometimes this generation script isn't atomic and races
with other compiles.  Since this script only exists to update the
linux_syscall_numbers.h header, and we commit that to git already,
there isn't a big need to run this all the time during build.

BUG=chromium:667204
TEST=precq passes

Change-Id: I1918031c867b150bee22fbdb8ba2f2914185de04
Reviewed-on: https://chromium-review.googlesource.com/1264896
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
diff --git a/testcases/kernel/include/regen.sh b/testcases/kernel/include/regen.sh
index c01bf1a..ddafab4 100755
--- a/testcases/kernel/include/regen.sh
+++ b/testcases/kernel/include/regen.sh
@@ -1,5 +1,9 @@
 #!/bin/sh
 
+# Disabled due to https://crbug.com/667204
+touch "linux_syscall_numbers.h"
+exit 0
+
 output="linux_syscall_numbers.h"
 rm -f "${output}".[1-9]*
 output_pid="${output}.$$"