Rename STRV_MAKE_EMPTY to just STRV_EMPTY

Even though this creates a stack allocation, it is not a function macro, so
drop the "make" from the name.

src/basic/macro.h

@@ -152,7 +152,7 @@ static inline unsigned long ALIGN_POWER2(unsigned long u) {
         } while (false)
 
 #define STRV_MAKE(...) ((char**) ((const char*[]) { __VA_ARGS__, NULL }))
-#define STRV_MAKE_EMPTY ((char*[1]) { NULL })
+#define STRV_EMPTY ((char*[1]) { NULL })
 #define STRV_MAKE_CONST(...) ((const char* const*) ((const char*[]) { __VA_ARGS__, NULL }))
 
 /* Pointers range from NULL to POINTER_MAX */