Revert "sysroot_lib: add -O to MAKEOPTS"

This reverts commit 2751fd7b489ea796b428b1ed1305e8d765b73d26.

Reason for revert: Blocking Chrome uprev, crbug.com/1167501

Original change's description:
> sysroot_lib: add -O to MAKEOPTS
>
> Now that we've had a new enough make for a while, turn on the -O
> option.  This tells make to group output from targets together and
> not intermingle everything which makes reading parallel build output
> a lot easier on humans.
>
> BUG=None
> TEST=CQ passes
>
> Change-Id: I98444ae9f609d0c1fd1f755eeaf3719442b5fb24
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2627105
> Reviewed-by: Sergey Frolov <sfrolov@google.com>
> Reviewed-by: Mike Frysinger <vapier@chromium.org>
> Tested-by: Mike Frysinger <vapier@chromium.org>
> Commit-Queue: Mike Frysinger <vapier@chromium.org>

Exempt-From-Owner-Approval: Fix chrome builds

Bug: 1167501
Change-Id: I9fe17415aa322f78c1a50c2e757cdff290868a39
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2634701
Tested-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Honglin Yu <honglinyu@chromium.org>
Commit-Queue: Manoj Gupta <manojgupta@chromium.org>
diff --git a/lib/sysroot_lib.py b/lib/sysroot_lib.py
index 575916c..a86fab9 100644
--- a/lib/sysroot_lib.py
+++ b/lib/sysroot_lib.py
@@ -509,7 +509,7 @@
     config['BOARD_OVERLAY'] = '\n'.join(board_overlays)
     config['PORTDIR_OVERLAY'] = '\n'.join(portdir_overlays)
 
-    config['MAKEOPTS'] = f'-O -j{multiprocessing.cpu_count()}'
+    config['MAKEOPTS'] = '-j%s' % str(multiprocessing.cpu_count())
     config['ROOT'] = self.path + '/'
     config['PKG_CONFIG'] = self._WrapperPath('pkg-config')