CA-292641: debug: use private buffer for logs formatter
CA-292641: debug: use private buffer for logs formatter

Instead of using a shared Format.stbuf with str_formatter - this might
cause problems when logging from multiple threads.

Signed-off-by: Gabor Igloi <7535f5501fd71876c93d896691e178fd3a11cfbb@citrix.com>

xapi-project/message-switch,xapi-project/message-switch,xapi-project/message-switch