Always install host sysroot when running install-sysroot.py
Always install host sysroot when running install-sysroot.py

The gn bots require both host and target sysrot images
installed.  This change is needed to convert the Linux
ARM bot gn.

BUG=564059

Review URL: https://codereview.chromium.org/1499313002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#363916}

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