trace: Use explicit alignment requirements to avoid misalignment

64-bit builds with CONFIG_WPA_TRACE=y resulted in the wpabuf pointers
getting misaligned (only 32-bit aligned) and that would result in reads
and writes of unaligned size_t values. Avoid this by indicating explicit
alignment requirement for wpabuf_trace to 8 octets (i.e., there will be
extra four octets of padding in case of 64-bit builds).

Similarly, struct os_alloc_trace resulted in some potential misalignment
cases, e.g., when CONFIG_ACS=y uses a 'long double' variable within
struct hostapd_channel_data. Avoid misalignment issues with explicit
alignment indication.

Signed-off-by: Jouni Malinen <j@w1.fi>

src/utils/os_unix.c

@@ -36,7 +36,7 @@ struct os_alloc_trace {
 	struct dl_list list;
 	size_t len;
 	WPA_TRACE_INFO
-};
+} __attribute__((aligned(16)));
 
 #endif /* WPA_TRACE */
 

src/utils/wpabuf.c

@@ -17,7 +17,7 @@
 
 struct wpabuf_trace {
 	unsigned int magic;
-};
+} __attribute__((aligned(8)));
 
 static struct wpabuf_trace * wpabuf_get_trace(const struct wpabuf *buf)
 {