configure: Disable automatic image base calculation

There's no reason for it.  ASLR will rebase it regardless so "preventing
collisions" isn't really relevant.  This also brings it in line with
what a msvc produced dll will have (an image base of 0x10000000).

Signed-off-by: Alex Smith <alex.smith@warpsharp.info>
Reviewed-by: Hendrik Leppkes <h.leppkes@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
