Prefer -U LD_PRELOAD over -drop-ld-preload
Prefer -U LD_PRELOAD over -drop-ld-preload

We want to get rid of the stupid -drop-ld-preload flag in qemu upstream.
Therefor mandatory for sb2 2.0. release :)

Only lightly tested but appears to work as expected.

Signed-off-by: Riku Voipio <1b2b12f1a98b3f96608883bfc38852bb84b0d6c5@iki.fi>

ldbox/ldbox,h113331pp/scratchbox2,lbt/scratchbox2,freedesktop-unofficial-mirror/sbox2,BinChengfei/scratchbox2,BinChengfei/scratchbox2,ldbox/ldbox,OlegGirko/ldbox,neeraj9/sbox2,BinChengfei/scratchbox2,h113331pp/scratchbox2,OlegGirko/ldbox,loganchien/scratchbox2,freedesktop-unofficial-mirror/sbox2,loganchien/scratchbox2,madscientist42/scratchbox2,madscientist42/scratchbox2,BinChengfei/scratchbox2,BinChengfei/scratchbox2,freedesktop-unofficial-mirror/sbox2,neeraj9/sbox2,freedesktop-unofficial-mirror/sbox2,OlegGirko/ldbox,lbt/scratchbox2,h113331pp/scratchbox2,freedesktop-unofficial-mirror/sbox2,h113331pp/scratchbox2,madscientist42/scratchbox2,neeraj9/sbox2,loganchien/scratchbox2,ldbox/ldbox,ldbox/ldbox,madscientist42/scratchbox2,h113331pp/scratchbox2,lbt/scratchbox2,neeraj9/sbox2,neeraj9/sbox2,h113331pp/scratchbox2,ldbox/ldbox,madscientist42/scratchbox2,lbt/scratchbox2,madscientist42/scratchbox2,ldbox/ldbox,OlegGirko/ldbox,neeraj9/sbox2,loganchien/scratchbox2,OlegGirko/ldbox,OlegGirko/ldbox,freedesktop-unofficial-mirror/sbox2,BinChengfei/scratchbox2,loganchien/scratchbox2,loganchien/scratchbox2,lbt/scratchbox2