gdb: fix typo in complaint in dwarf2/macro.c

gdb: fix typo in complaint in dwarf2/macro.c

I saw this complaint when my code had some bug, and spotted the typo.
Fix it, and while at it mention DW_MACRO as well (it would be confusing
to only see DW_MACINFO with a file that uses a DWARF 5 .debug_macro
section).  I contemplated the idea of passing the knowledge of whether
we are dealing with a .debug_macro section or .debug_macinfo section, to
print only the right one.  But in the end, I don't think that trouble is
necessary for a complaint nobody is going to see.

Change-Id: I276ce8da65c3eac5304f64a1e246358ed29cdbbc