Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/bb6388045214
Author: Carsten Book <tomcat@mozilla.com>
Desc: Merge pull request #24944 from ochameau/bug1079865

Bug 1079865 - Fix gaia build system on windows, r=gduan

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https://hg.mozilla.org/integration/gaia-central/rev/8495faec1266
Author: Alexandre Poirot <poirot.alex@gmail.com>
Desc: Bug 1079865 - Fix gaia build system on windows. r=gduan
Bumping manifests a=b2g-bump