dashboard/app: don't show empty compiler/CC
dashboard/app: don't show empty compiler/CC

Compiler and CC can be empty, don't show them if they are empty.

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