Use SHA-1 in TLS 1.2 client auth if the server requests it.

Consider the signature algorithms requested by the server in addition to those
supported by the client key in ssl3_DestroyBackupHandshakeHashIfNotNeeded.
This also takes the client key's signature algorithm into account.

BUG=325254
TEST=manual testing by bug reporter

Review URL: https://codereview.chromium.org/102663002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238730 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238730