tools/syz-kconf: apply replacement vars to Compiler as well
tools/syz-kconf: apply replacement vars to Compiler as well

This allows to use compiler dependent on arch and/or from kernel build/source dir.

google/syzkaller,google/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller,xairy/syzkaller,xairy/syzkaller,xairy/syzkaller,google/syzkaller,google/syzkaller,google/syzkaller,xairy/syzkaller,xairy/syzkaller,google/syzkaller