[clang] [clang-format] Add -r option for recursing into directories (PR #160299)

[via cfe-commits]

mydeveloperday wrote:

if we were going to do this... wouldn't   something like --glob  '**/dir/*.cpp' be nicer to support? than doing just -r .

clang-format  --glob  '**/src/*.cpp' --glob  '**/include/*.h'

https://github.com/llvm/llvm-project/pull/160299