Instrumented libraries: never run `make install' in parallel.

For some packages this causes flaky failures such as described in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42980

BUG=313751
TBR=glider@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/365923003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@281025 0039d316-1c4b-4281-b951-d872f2087c98