Android NDK: UNIX_PATH_MAX is defined in un.h

in Android NDK, UNIX_PATH_MAX is already defined,
add ifndef to check.

linux/un.h:
22: #define UNIX_PATH_MAX 108

Cc: Chen Hu <hu1.chen@intel.com>
Signed-off-by: Zhang Ning <ning.a.zhang@intel.com>
Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>

compel/src/lib/infect.c

@@ -33,8 +33,10 @@
 #include "common/scm.h"
 #include "common/scm-code.c"
 
+#ifndef UNIX_PATH_MAX
 #define UNIX_PATH_MAX (sizeof(struct sockaddr_un) - \
 			(size_t)((struct sockaddr_un *) 0)->sun_path)
+#endif
 
 #define PARASITE_STACK_SIZE	(16 << 10)
 

criu/include/util-pie.h

@@ -4,8 +4,10 @@
 #include <sys/socket.h>
 #include <sys/un.h>
 
+#ifndef UNIX_PATH_MAX
 #define UNIX_PATH_MAX (sizeof(struct sockaddr_un) - \
 			(size_t)((struct sockaddr_un *) 0)->sun_path)
+#endif
 
 #ifndef SO_PEEK_OFF
 #define SO_PEEK_OFF            42