SwiftCompile should include headers if bridging header is presented

Created by: fkorotkov

It seems when a bridging header is presented header symlink trees should be provided to swift compiler via -I flag.

I've created an example here: https://github.com/fkorotkov/buck-sandbox/commit/46d25d39a07f52f3e2f981d080c1eef0845ca26d

Basically my bridging header next to a BUCK file has #import "objc/Foo.h" and objc/Foo.h contains #import "Version.h" where Version.h suppose to be next to the BUCK file as well. With this special setup I'm getting:

complex_objc_swift/Foo-Bridging-Header.h:1:
#import "objc/Foo.h"
        ^
/Users/fedor_korotkov/workspace/buck-sandbox/complex_objc_swift/objc/Foo.h:3:9: error: 'Version.h' file not found
#import "Version.h"
        ^
<unknown>:0: error: failed to import bridging header 'complex_objc_swift/Foo-Bridging-Header.h'

I was able to fix the command line by adding -I complex_objc_swift.