Hello,

The attached impements PPC64 SYSV specific versions of:

	use_struct_convention
	extract_return_value
	store_return_value

It fixes:

gdb.base/return2.exp: char value returned successfully
gdb.base/return2.exp: int value returned successfully
gdb.base/return2.exp: short value returned successfully
gdb.base/structs.exp: p fun1
gdb.base/structs.exp: p fun2
gdb.base/structs.exp: p fun3
gdb.base/structs.exp: p fun4
gdb.base/structs.exp: p fun5
gdb.base/structs.exp: p fun6
gdb.base/structs.exp: p fun7
gdb.base/structs.exp: p fun8
gdb.c++/userdef.exp: print !one
gdb.c++/userdef.exp: print -one
gdb.c++/userdef.exp: print one != two
gdb.c++/userdef.exp: print one % two
gdb.c++/userdef.exp: print one & two
gdb.c++/userdef.exp: print one && two
gdb.c++/userdef.exp: print one * two
gdb.c++/userdef.exp: print one + two
gdb.c++/userdef.exp: print one - two
gdb.c++/userdef.exp: print one / two
gdb.c++/userdef.exp: print one < two
gdb.c++/userdef.exp: print one << 31
gdb.c++/userdef.exp: print one <= two
gdb.c++/userdef.exp: print one == two
gdb.c++/userdef.exp: print one > two
gdb.c++/userdef.exp: print one >= two
gdb.c++/userdef.exp: print one >> 31
gdb.c++/userdef.exp: print one ^ two
gdb.c++/userdef.exp: print one | two
gdb.c++/userdef.exp: print one || two
gdb.c++/userdef.exp: print ~one
gdb.c++/userdef.exp: re-selected 'main' frame after inferior call

Note the way I implemented it - the above wrap a generic 
ppc64_sysv_abi_return_value function and that handles all cases.  I was 
finding that the more traditional technique (per my ppc post) was too 
error proned.  Converting it to this style caused several mysterious 
regressions to mysteriously disappear.

I'm thinking of proposing that this technique become the norm.

Anyway, ok to commit?
Andrew

PS: I should note that PPC64's call function code is still on life 
support - it's not in a good shape at all.