Adding libssl-dev to the list of packages required for chrome development.

Adding libssl-dev to the list of packages required for chrome development.
Chrome uses an explicit third_party copy of this library,
however, temporarily the nacl_integration_tests require the system
version to be installed to build sel_ldr.

BUG=http://code.google.com/p/nativeclient/issues/detail?id=2265
TEST=None
R=nfullagar@google.com
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=102188

[nfullagar, 2011-09-21 23:13:24]

lgtm