Use installExecutable for cc binaries

Normally InstallFile is enough because linker grants +x permission to
its output. Just to guarantee +x permission even when the source file
doesn't have one.

Test: build
Change-Id: I01082df11d414804e1a73336fc637a6a2208021f
diff --git a/cc/binary.go b/cc/binary.go
index 496c610..097f822 100644
--- a/cc/binary.go
+++ b/cc/binary.go
@@ -512,7 +512,7 @@
 		}
 		binary.baseInstaller.subDir = "bootstrap"
 	}
-	binary.baseInstaller.install(ctx, file)
+	binary.baseInstaller.installExecutable(ctx, file)
 
 	var preferredArchSymlinkPath android.OptionalPath
 	for _, symlink := range binary.symlinks {