r19093: speed up the samba3 build from 8mins to 5mins:-)

r19093: speed up the samba3 build from 8mins to 5mins:-)

we now don't compile mostly each .c file twice.

- we use PICFLAG for all object files
- PICFLAG defaults to PIE_CFLAGS and is then overwritten
  if the system supports shared libraries

as we currently always use -fPIE if available
(and at least on linux -fPIE produces the same code as -fPIC)
it doesn't change anything in the resulting code.

"high performance" binaries can be build with
"--disable-pie --disable-shared" if someone really needs to...

metze