use PACKED macro insted of open-coding GCC-ism

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/archival/libunarchive/decompress_unlzma.c b/archival/libunarchive/decompress_unlzma.c
index 4478cd2..ecda174 100644
--- a/archival/libunarchive/decompress_unlzma.c
+++ b/archival/libunarchive/decompress_unlzma.c
@@ -156,7 +156,7 @@
 	uint8_t pos;
 	uint32_t dict_size;
 	uint64_t dst_size;
-} __attribute__ ((packed)) lzma_header_t;
+} PACKED lzma_header_t;
 
 
 /* #defines will force compiler to compute/optimize each one with each usage.
diff --git a/archival/libunarchive/decompress_unzip.c b/archival/libunarchive/decompress_unzip.c
index b090f26..c571ab4 100644
--- a/archival/libunarchive/decompress_unzip.c
+++ b/archival/libunarchive/decompress_unzip.c
@@ -1117,7 +1117,7 @@
 			uint32_t mtime;
 			uint8_t xtra_flags_UNUSED;
 			uint8_t os_flags_UNUSED;
-		} __attribute__((packed)) formatted;
+		} PACKED formatted;
 	} header;
 	struct BUG_header {
 		char BUG_header[sizeof(header) == 8 ? 1 : -1];