Fix compilation for MSVC

"inline" is not supported in C89. (and make the prototypes
look like the rest of the project)

Change-Id: Ie64f3f012dcb75ee6b150d4d2d63f37f20921081
Reviewed-on: http://review.couchbase.org/27593
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>