scripts/oe-buildenv-internal: Add SOCKS5_{USER, PASSWD} to BB_ENV_EXTRAWHITE

scripts/oe-buildenv-internal: Add SOCKS5_{USER, PASSWD} to BB_ENV_EXTRAWHITE

If a SOCKS5 gateway is needed for a proxy access like git it might also
require authentication to the proxy via a password and username.  Adding
SOCKS5_USER & SOCKS5_PASSWD to BB_ENV_EXTRAWHITE allow for automation
of the authentication request to occur when something like a git fetch
is going through the proxy.

This patch requires the bitbake patch to add extra exportvars so
these variables get passed from Env -> bitbake -> fetcher

(From OE-Core rev: 9206ea0f7cd39d2ba6ff4b41cbeb17409d3ae5f1)

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Matthew McClintock <msm@freescale.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>