tree d27732625b4e9b0378eb2697ca391604ea71cd34
parent 83e9cfe291c7acde13e36101bb82f66eff59a9af
author Dan Willemsen <dwillemsen@google.com> 1591667414 -0700
committer Dan Willemsen <dwillemsen@google.com> 1591668623 -0700

More performance improvements

Instead of using `x := $(x) foo`, make sure `x` is initialized first,
then use `x += foo`.

For a aosp-master/aosp_crosshatch-userdebug build, this takes the build
from 49s to 33s (no significant difference in peak memory)

Bug: 158488548
Test: build-aosp_crosshatch.ninja is the same before/after
Change-Id: I41fb7611030dd3ba824f896a9c9eadbdd218f464