libfec: pack the fec_header structure

The fec_header structure is generated build time and stored on disk.
The fec_header might be build on a 64 bits machine while it is read
per a 32 bits device or the other way around.  In such situations, the
fec_header fields are not aligned as expected by the device and it
fails to read the fec_header structure.

This patch makes the fec_header packed.

Change-Id: I77546f850cea5559909971a1192e1a7616d22d50
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
diff --git a/libfec/include/fec/io.h b/libfec/include/fec/io.h
index 3b5dac0..670a5d7 100644
--- a/libfec/include/fec/io.h
+++ b/libfec/include/fec/io.h
@@ -49,7 +49,7 @@
     uint32_t fec_size;
     uint64_t inp_size;
     uint8_t hash[SHA256_DIGEST_LENGTH];
-};
+} __attribute__ ((packed));
 
 struct fec_status {
     int flags;