Add void cast to StaticAssertExpr?

While poking around in buildfarm results, I noticed that some members are
giving warnings like

analyze.c:386:181: warning: expression result unused [-Wunused-value]

which is apparently caused by the use of StaticAssertExpr in

#define AllocSetContextCreate(parent, name, allocparams) \
(StaticAssertExpr(__builtin_constant_p(name), \
"Use AllocSetContextCreateExtended with MEMCONTEXT_COPY_NAME for non-constant context names"), \
AllocSetContextCreateExtended(parent, name, 0, allocparams))

Now, I could silence those warnings via

- (StaticAssertExpr(__builtin_constant_p(name), \
+ ((void) StaticAssertExpr(__builtin_constant_p(name), \

as I see has already been done in two similar uses of StaticAssertExpr in
c.h. However, this seems a bit silly. Wouldn't it be better to put
the void cast right into StaticAssertExpr?

regards, tom lane