Do not execute linkerconfig from recovery

Linkerconfig binary itself should be built as static, so size of
executable is hard to be reduced. However, this used lots of space from
recovery so only small space left in it. To avoid this linker config
from recovery should be generated within build time and use prebuilt
one. Prebuilt ld.config.txt will be located under /system/etc as before,
and init will copy the file into /linkerconfig so we can use same
location for both recovery and normal boot.

Bug: 146384333
Test: m -j passed && crosshatch bootloader worked with this change
Change-Id: I96300f1c8301167234787274820086a4c6ea0e6e