Add le16toh defines for platforms that may be missing it.

miner.h

@@ -159,6 +159,7 @@ static inline int fsync (int fd)
 #ifndef htobe32
 # if __BYTE_ORDER == __LITTLE_ENDIAN
 #  define htole16(x) (x)
+#  define le16toh(x) (x)
 #  define htole32(x) (x)
 #  define htole64(x) (x)
 #  define le32toh(x) (x)
@@ -169,6 +170,7 @@ static inline int fsync (int fd)
 #  define htobe64(x) bswap_64(x)
 # elif __BYTE_ORDER == __BIG_ENDIAN
 #  define htole16(x) bswap_16(x)
+#  define le16toh(x) bswap_16(x)
 #  define htole32(x) bswap_32(x)
 #  define le32toh(x) bswap_32(x)
 #  define le64toh(x) bswap_64(x)