[DWARVES]: Print the bit offset too

Helps understanding how bitfields really work, and after all it is just
confusing, not wrong.

See this one:

struct usb_bus {
	struct device *      controller;       /*   0     8 */
	int                  busnum;           /*   8     4 */

	/* XXX 4 bytes hole, try to pack */

	char *               bus_name;         /*  16     8 */
	u8                   uses_dma;         /*  24     1 */
	u8                   otg_port;         /*  25     1 */

	/* WARNING: DWARF offset=24, real offset=26 */

	unsigned int         is_b_host:1;      /*  24:15  4 */
	unsigned int         b_hnp_enable:1;   /*  24:14  4 */

	/* XXX 30 bits hole, try to pack */

	int                  devnum_next;      /*  28     4 */
<SNIP>
};

So the bitfield _really_ is at offset 24 and the "WARNING:" above is just
pahole not understanding how it works, i.e. it starts at 24 and since the
bitfield has a 'unsigned int' as its base type it goes from 24 to 27, the
offsets start at the end, i.e. from byte 27 back to byte 27, but as only two
bits are used, it puts bit padding at the end, at bit offset 0, that is the
last bit in byte 27 and uses the first bits of byte 26 at bit offset 14 and 15.

Now to make libdwarves finally understand this convention.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

dwarves.c

@@ -1478,10 +1478,20 @@ static size_t struct_member__fprintf(struct class_member *self,
 			printed += p;
 			spacing -= p;
 		}
-		if (!sconf.suppress_offset_comment)
-			printed += fprintf(fp, "%*s/* %5u %5u */",
+		if (!sconf.suppress_offset_comment) {
+			size_t size_spacing = 5;
+
+			printed += fprintf(fp, "%*s/* %5u",
 					   spacing > 0 ? spacing : 0, " ",
-					   offset, size);
+					   offset);
+
+			if (self->bit_size != 0) {
+				printed += fprintf(fp, ":%2d", self->bit_offset);
+				size_spacing -= 3;
+			}
+
+			printed += fprintf(fp, " %*u */", size_spacing, size);
+		}
 	}
 	return printed;
 }