Allow C++ applications to include symtab header

The RMR symbol table functions are exposed to xAPPs, however the
header file lacked the magic C++ goo that allowed it to be included.
This change adds the goo, and changes a parameter name in the
prototypes to avoide a collision with C++ reserved words.

Issue-ID: RIC-522

Signed-off-by: E. Scott Daniels <daniels@research.att.com>
Change-Id: Idadaa109d191b0de0629737f27d2444a4e581e64