Incremental build fails (missing dep declarations for std lib), requires expunge

With incremental builds, I see errors like

```
ERROR: /usr/local/google/home/gcmn/.cache/bazel/_bazel_gcmn/151032d5e60e04f24eb0914f43c91bbf/external/com_google_absl/absl/base/BUILD.bazel:145:1: undeclared inclusion(s) in rule '@com_google_absl//absl/base:malloc_internal':
this rule is missing dependency declarations for the following files included by 'external/com_google_absl/absl/base/internal/low_level_alloc.cc':
'/usr/lib/clang/9.0.1/include/stddef.h'
'/usr/lib/clang/9.0.1/include/stdint.h'
'/usr/lib/clang/9.0.1/include/limits.h'
'/usr/lib/clang/9.0.1/include/__stddef_max_align_t.h'
'/usr/lib/clang/9.0.1/include/stdarg.h'
```

The specific starting point varies (not always absl), but it's always an include of some std header. Building with RBE worked, so I think it's something specific about the local state. `bazel clean` was insufficient to fix the issue, but `bazel clean --expunge` made it go away. Per the instructions at https://docs.bazel.build/versions/master/user-manual.html#the-clean-command, I'm filing a bug.

Please let me know what additional information I can provide, although I suspect some things may be lost now that I've run expunge.

Start by reproducing the incremental-build failure involving external/com_google_absl/absl/base/BUILD.bazel and low_level_alloc.cc, noting the missing Clang standard headers. Compare local incremental builds with RBE, then test the reported difference between bazel clean and bazel clean --expunge. Done means identifying the local-state cause and adding a regression test or documented fix.

Written by the indexing model from the issue text.