Propagate unexported deps via implementation_deps

Test: bp2build and mixed_libc CI
Test: Manually verified that libc_bionic_ndk compilation gets the
appropriate headers (and no extra headers) from downstream

Change-Id: I79eb6e8ec1d415bd50d12105da4cf97101f95474

bp2build/cc_library_conversion_test.go

@@ -115,7 +115,7 @@ cc_library {
         "-I.",
         "-I$(BINDIR)/.",
     ],
-    deps = [":some-headers"],
+    implementation_deps = [":some-headers"],
     includes = ["foo-dir"],
     linkopts = ["-Wl,--exclude-libs=bar.a"] + select({
         "//build/bazel/platforms/arch:x86": ["-Wl,--exclude-libs=baz.a"],
@@ -186,7 +186,7 @@ cc_library {
         "-I.",
         "-I$(BINDIR)/.",
     ],
-    deps = [":libc_headers"],
+    implementation_deps = [":libc_headers"],
     linkopts = [
         "-Wl,--exclude-libs=libgcc.a",
         "-Wl,--exclude-libs=libgcc_stripped.a",
@@ -317,10 +317,10 @@ cc_library { name: "shared_dep_for_both" }
         "-Ifoo/bar",
         "-I$(BINDIR)/foo/bar",
     ],
-    deps = [":static_dep_for_both"],
     dynamic_deps = [":shared_dep_for_both"],
     dynamic_deps_for_shared = [":shared_dep_for_shared"],
     dynamic_deps_for_static = [":shared_dep_for_static"],
+    implementation_deps = [":static_dep_for_both"],
     shared_copts = ["sharedflag"],
     shared_srcs = ["sharedonly.cpp"],
     srcs = ["both.cpp"],