tests: avoid using eval with variable assignments

tests: avoid using eval with variable assignments

For shell portability, avoid using eval with variable assignments to set
openconnect's environment. Shell implementations vary on whether
variable assignments in front of eval are marked as environment
variables or just treated as ordinary shell assignments.

Every call to $OPENCONNECT already has LD_PRELOAD=libsocket_wrapper.so
in front of it, so the "eval LD_PRELOAD=libsocket_wrapper.so" was
redundant anyway.

Signed-off-by: Mike Miller <mtmiller@debian.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>