devel/cdecl: update to 16.1

ChangeLog:
explicit-ecsu in English
The value of the explicit-ecsu option now also applies in pseudo-English. Previously:

c++decl> class C
c++decl> explain C *p
declare p as pointer to C
Now (with explicit-ecsu containing c):

c++decl> class C
c++decl> set explicit-ecsu = csu
c++decl> explain C *p
declare p as pointer to class C
Leading/trailing whitespace stringification
Previously:

expand Q2(, a b ,)
incorrectly returned " a b " whereas now it correctly returns "a b".