This is the version 3 of patch 4/4.  In this version,
setup_kfail_for_target is used to KFAIL the same fail to different PRs
according to target triplet, same as what I did in patch 3/4.

Run callfuncs.exp with this patch applied on three different targets.
Note that there is one extra FAIL in i686-pc-linux-gnu and
armv7l-unknown-linux-gnueabi, caused by these KFAILs.

i686-pc-linux-gnu:
KFAIL: gdb.base/callfuncs.exp: call inferior func with struct - returns
double _Complex (PRMS: gdb/12783)
KFAIL: gdb.base/callfuncs.exp: call inferior func with struct - returns
long double _Complex (PRMS: gdb/12783)
FAIL: gdb.base/callfuncs.exp: gdb function calls preserve register contents

armv7l-unknown-linux-gnueabi:
KFAIL: gdb.base/callfuncs.exp: call inferior func with struct - returns
float _Complex (PRMS: gdb/12797)
KFAIL: gdb.base/callfuncs.exp: call inferior func with struct - returns
double _Complex (PRMS: gdb/12797)
KFAIL: gdb.base/callfuncs.exp: call inferior func with struct - returns
long double _Complex (PRMS: gdb/12797)
FAIL: gdb.base/callfuncs.exp: gdb function calls preserve register contents

x86_64-pc-linux-gnu:
KFAIL: gdb.base/callfuncs.exp: p t_float_complex_values(fc1, fc2) (PRMS:
gdb/12798)
KFAIL: gdb.base/callfuncs.exp: p t_float_complex_many_args(fc1, fc2,
fc3, fc4, fc1, fc2, fc3, fc4, fc1, fc2, fc3, fc4, fc1, fc2, fc3, fc4)
(PRMS: gdb/12800)
KFAIL: gdb.base/callfuncs.exp: p t_double_complex_values(dc1, dc2)
(PRMS: gdb/12798)
KFAIL: gdb.base/callfuncs.exp: p t_double_complex_many_args(dc1, dc2,
dc3, dc4, dc1, dc2, dc3, dc4, dc1, dc2, dc3, dc4, dc1, dc2, dc3, dc4)
(PRMS: gdb/12800)
KFAIL: gdb.base/callfuncs.exp: call inferior func with struct - returns
float _Complex (PRMS: gdb/12796)
KFAIL: gdb.base/callfuncs.exp: call inferior func with struct - returns
double _Complex (PRMS: gdb/12796)
KFAIL: gdb.base/callfuncs.exp: call inferior func with struct - returns
long double _Complex (GDB internal error) (PRMS: gdb/12796)

-- 
Yao (齐尧)