Disable tidy checks for generated code

Generated codes like cpp code from *.ll for *.yy files always run
clang-tidy, when generated code has warning, where is no way to fix it.

So, disable clang-tidy for generated code.

Bug: 162909698
Test: go test android/soong/cc
Change-Id: I0fee137d6170ef4bf6cf641abad572e448aceaa1