libctf: fix handling of CTF symtypetab sections emitted by older GCC

libctf: fix handling of CTF symtypetab sections emitted by older GCC

Older (pre-upstreaming) GCC emits a function symtypetab section of a
format never read by any extant libctf.  We can detect such CTF dicts by
the lack of the CTF_F_NEWFUNCINFO flag in their header, and we do so
when reading in the symtypetab section -- but if the set of symbols with
types is sufficiently sparse, even an older GCC will emit a function
index section.

In NEWFUNCINFO-capable compilers, this section will always be the exact
same length as the corresponding function section (each is an array of
uint32_t, associated 1:1 with each other). But this is not true for the
older compiler, for which the sections are different lengths.  We check
to see if the function symtypetab section and its index are the same
length, but we fail to skip this check when this is not a NEWFUNCINFO
dict, and emit a spurious corruption error for a CTF dict we could
have perfectly well opened and used.

Fix trivial: check the flag (and fix the terrible grammar of the error
message at the same time).

libctf/ChangeLog
2021-09-27  Nick Alcock  <nick.alcock@oracle.com>

	* ctf-open.c (ctf_bufopen_internal): Don't complain about corrupt
	function index symtypetab sections if this is an old-format
	function symtypetab section (which should be ignored in any case).
	Fix bad grammar.