Add --no-ndk to ndkstubgen

By default, ndkstubgen does not omit NDK symbols as long as they
satisfy the API version and the CPU architecture requirements. This
change adds a new flag --no-ndk to ndkstubgen which is used to
override the default behavior. If the flag is set, NDK symbols are
omitted leaving only the annotated symbols (e.g. #apex, #systemapi,
etc.).

This will be used for stub libraries that are not part of NDK. So far,
symbols in such libraries haven't needed to be annotated as #apex, and
that has caused a confusion that those symbols belong to NDK. The
follow-up change will ensure that those symbols are always annoated as
either #apex or #systemapi so that their roles are clearly visible.

Bug: 184712170
Test: atest test_ndkstubgen
Test: atest test_symbolfile
Change-Id: Ic8d2c7d0b32bdef79f7563621035e60f406e4131
diff --git a/cc/symbolfile/__init__.py b/cc/symbolfile/__init__.py
index 471a12f..9bf07f2 100644
--- a/cc/symbolfile/__init__.py
+++ b/cc/symbolfile/__init__.py
@@ -208,12 +208,14 @@
     symbol should be omitted or not
     """
 
-    def __init__(self, arch: Arch, api: int, llndk: bool = False, apex: bool = False, systemapi: bool = False):
+    def __init__(self, arch: Arch, api: int, llndk: bool = False, apex: bool = False, systemapi:
+                 bool = False, ndk: bool = True):
         self.arch = arch
         self.api = api
         self.llndk = llndk
         self.apex = apex
         self.systemapi = systemapi
+        self.ndk = ndk
 
     def _should_omit_tags(self, tags: Tags) -> bool:
         """Returns True if the tagged object should be omitted.
@@ -253,8 +255,13 @@
 
     def should_omit_symbol(self, symbol: Symbol) -> bool:
         """Returns True if the symbol should be omitted."""
-        return self._should_omit_tags(symbol.tags)
+        if not symbol.tags.has_mode_tags and not self.ndk:
+            # Symbols that don't have mode tags are NDK. They are usually
+            # included, but have to be omitted if NDK symbols are explicitly
+            # filtered-out
+            return True
 
+        return self._should_omit_tags(symbol.tags)
 
 def symbol_in_arch(tags: Tags, arch: Arch) -> bool:
     """Returns true if the symbol is present for the given architecture."""
diff --git a/cc/symbolfile/test_symbolfile.py b/cc/symbolfile/test_symbolfile.py
index e17a8d0..856b9d7 100644
--- a/cc/symbolfile/test_symbolfile.py
+++ b/cc/symbolfile/test_symbolfile.py
@@ -308,6 +308,20 @@
     def assertInclude(self, f: Filter, s: Symbol) -> None:
         self.assertFalse(f.should_omit_symbol(s))
 
+    def test_omit_ndk(self) -> None:
+        f_ndk = self.filter
+        f_nondk = copy(f_ndk)
+        f_nondk.ndk = False
+        f_nondk.apex = True
+
+        s_ndk = Symbol('foo', Tags())
+        s_nonndk = Symbol('foo', Tags.from_strs(['apex']))
+
+        self.assertInclude(f_ndk, s_ndk)
+        self.assertOmit(f_ndk, s_nonndk)
+        self.assertOmit(f_nondk, s_ndk)
+        self.assertInclude(f_nondk, s_nonndk)
+
     def test_omit_llndk(self) -> None:
         f_none = self.filter
         f_llndk = copy(f_none)