Added generation of the llvm 'sret' parameter attribute where applicable. Fixed some wrong argument handling code when setting parameter attributes. Updated the tango unittest script in the tango patch, does not work yet, all modules don't compile...

syntax: glob
tests/dstress
tests/reference
*.bc
*.o
*.s
*.a
obj/*
tango
import
Makefile
bin/llvmdc
idgen
idgen.make
impcnvgen
impcnvgen.make
llvmdc.make
dmd/impcnvtab.c
tests/runminitest
tests/findregressions
tests/mini/obj/*