stage1: Ask LLVM to produce compact code in ReleaseSize mode
Let's follow what Clang does for -Oz and apply the `minsize` and
`optsize` attributes by default.
Closes #7048
Supersedes #7077
10b1001a12LemonBoy committed on 11/13/2020, 5:27:26 PM· committed by Andrew Kelleyparenteaa1db2