[clang] [clang][Driver] Add flag for setting SkipFunctionBodies (PR #100135)

[kadir çetinkaya via cfe-commits]

kadircet wrote:

> That said, so long as this is a -cc1-only option, it seems reasonable to m

this is a cc1-only option. added test, updated the commit message.

https://github.com/llvm/llvm-project/pull/100135