gdb: use std::string vector for macro definition

gdb: use std::string vector for macro definition

Use std::vector<std::string> when defining macros, to avoid the manual
memory management.

With the use of std::vector, the separate `int argc` parameter is no
longer needed, we can use the size of the vector instead.  However, for
some functions, this parameter had a dual function.  For object-like
macros, it was interpreted as a `macro_special_kind` enum.  For these
functions, remove `argc`, but add a new `special_kind` parameter.

Change-Id: Ice76a6863dfe598335e3b8d5d077513e50975cc5
Approved-By: Tom de Vries <tdevries@suse.de>