bash 4.0 compatibility for .keystone_install. In bash 4.0, "declare VAR" no longer initializes VAR if not already set.
bash 4.0 compatibility for .keystone_install. In bash 4.0, "declare VAR" no
longer initializes VAR if not already set.

BUG=83180
TEST=Run .keystone_install under bash 4.0 or newer (4.2.10 is current)
Review URL: http://codereview.chromium.org/7050012

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@85947 0039d316-1c4b-4281-b951-d872f2087c98

yitian134/chromium,gavinp/chromium,ropik/chromium,ropik/chromium,adobe/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,gavinp/chromium,adobe/chromium,adobe/chromium,ropik/chromium,gavinp/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,adobe/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,yitian134/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,adobe/chromium,yitian134/chromium,gavinp/chromium,gavinp/chromium,adobe/chromium,gavinp/chromium,gavinp/chromium,adobe/chromium,ropik/chromium,yitian134/chromium,yitian134/chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,ropik/chromium,ropik/chromium