rpmio: Include rpmmacro.h to fix compilation warning

rpmio.c: In function 'get_compression_threads':
rpmio.c:2114:12: warning: implicit declaration of function 'rpmExpandNumeric' [-Wimplicit-function-declaration]
 2114 |  threads = rpmExpandNumeric("%{getncpus}");
      |            ^~~~~~~~~~~~~~~~

Reported-by: Dmitry V. Levin <ldv@altlinux.org>

rpmio/rpmio.c

@@ -72,6 +72,7 @@ static int inet_aton(const char *cp, struct in_addr *inp)
 
 #include "ugid.h"
 #include "rpmmessages.h"
+#include "rpmmacro.h"
 
 #include "debug.h"