Summary:
Use the output of `clang -###` to drive which commands to run. Attach the plugin to all commands starting with `-cc1`.
Benefits:
- support for compiling multiple files in one clang command, eg `infer -- clang -c file1.c file2.c`
- support for compile commands that do not target a `.o` file, eg `infer -- clang -S hello.c`
- support for `-cc1` compile commands
- more generally, run all commands that clang would run, and attach plugin in all compilation cases
Reviewed By: martinoluca
Differential Revision: D3366912
fbshipit-source-id: 98d5e3b
Jules Villard