fastboot: Allow searching for needed dynamic libs in '.' (F2FS)

Currently the default rpath includes $ORIGIN/../lib
So we throw in '.' which should help distributions of fastboot.

readelf -d $(which fastboot)|grep RPATH
 0x0000000f (RPATH) Library rpath: [$ORIGIN/../lib:.]

Bug: 15731906
Change-Id: I2f4345d178e5b3c87f6f159faf105ae30f3b52eb
Signed-off-by: JP Abgrall <jpa@google.com>