Add cscope.out and .d files to .gitignore

cscope.out is generated by cscope as described in:
http://wiki.openssl.org/index.php/Testing_and_Development_Tools_and_Tips



.d files are compiler-generated Makefile dependency files (e.g. using
'gcc -MMD -MP foo.c').

Change-Id: I2338858a6b6ee0527837d10a8b55cff1689023fd
Signed-off-by: Mike Bland <mbland@acm.org>
Signed-off-by: Geoff Thorpe <geoff@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>