Auto merge of #12878 - fasterthanlime:standalone-pms-exe, r=lnicola
Auto merge of #12878 - fasterthanlime:standalone-pms-exe, r=lnicola

Find standalone proc-macro-srv on windows too

I forgot that executables end with `.exe` on Windows in:

  * https://github.com/rust-lang/rust-analyzer/pull/12858

rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer