Hello,

(Hmm, this is looking less painful than I thought ...  Nope ...)

Per Tom Tromey's long-a-go recommendation, this patch imports the latest 
AM_PROG_CC_STDC from automake.  It tweaks things so that:

+# HP-UX 10.20 and later        -Ae
+# HP-UX older versions -Aa -D_HPUX_SOURCE

are used.  I'm pretty sure that -Ae works on 10.20 and 11.00 and I'm not 
to worried about anything prior to that.
I've committed the attached to the 5.2 branch and GDB mainline.

Andrew

PS: The tally so far: gmake is needed; fix to libiberty needed; hpread.c 
doesn't compile; ...