I tried building gdb6.6 using snv_53 (from opensolaris.org) with sun
studio C 5.8.

SunOS swift 5.11 snv_53 i86pc i386 i86pc
./configure  --target=armel-linux
cc: Sun C 5.8 2005/10/13

the build fails because of:
"wrapper.c", line 773: void function cannot return value
".././gdb/cli/cli-cmds.c", line 517: void function cannot return value
"target.c", line 1248: void function cannot return value
"target.c", line 1264: void function cannot return value

the fix (cvs diff attached) is to replace
return (void) foo();
with
foo(); return;
if foo(); is the last statement, omit the return.