Rollup merge of #145452 - Kobzol:bootstrap-strip, r=jieyouxu

Do not strip binaries in bootstrap everytime if they are unchanged

I was profiling bootstrap to figure out why a no-op build takes upward of two seconds on my machine. I found that half of that is Cargo (which is mostly unavoidable) and the rest (~900ms) is running strip. We don't need to restrip already stripped binaries all the time.

r? `@jieyouxu`

Author: jieyouxu