Add support for weak symbols in the NDK stubs.

Test: nose2
Bug: None
Change-Id: I202f718103f4a645b1eb83c0a9f5313bcdb4d485
diff --git a/cc/gen_stub_libs.py b/cc/gen_stub_libs.py
index bed718c..abb39c2 100755
--- a/cc/gen_stub_libs.py
+++ b/cc/gen_stub_libs.py
@@ -347,10 +347,16 @@
                 if section_versioned and emit_version:
                     self.version_script.write('        ' + symbol.name + ';\n')
 
+                weak = ''
+                if 'weak' in symbol.tags:
+                    weak = '__attribute__((weak)) '
+
                 if 'var' in symbol.tags:
-                    self.src_file.write('int {} = 0;\n'.format(symbol.name))
+                    self.src_file.write('{}int {} = 0;\n'.format(
+                        weak, symbol.name))
                 else:
-                    self.src_file.write('void {}() {{}}\n'.format(symbol.name))
+                    self.src_file.write('{}void {}() {{}}\n'.format(
+                        weak, symbol.name))
 
             if not version_empty and section_versioned:
                 base = '' if version.base is None else ' ' + version.base
diff --git a/cc/test_gen_stub_libs.py b/cc/test_gen_stub_libs.py
index 4df6cf8..b20a5c7 100755
--- a/cc/test_gen_stub_libs.py
+++ b/cc/test_gen_stub_libs.py
@@ -430,6 +430,8 @@
             gsl.Version('VERSION_1', None, [], [
                 gsl.Symbol('foo', []),
                 gsl.Symbol('bar', ['var']),
+                gsl.Symbol('woodly', ['weak']),
+                gsl.Symbol('doodly', ['weak', 'var']),
             ]),
             gsl.Version('VERSION_2', 'VERSION_1', [], [
                 gsl.Symbol('baz', []),
@@ -443,6 +445,8 @@
         expected_src = textwrap.dedent("""\
             void foo() {}
             int bar = 0;
+            __attribute__((weak)) void woodly() {}
+            __attribute__((weak)) int doodly = 0;
             void baz() {}
             void qux() {}
         """)
@@ -453,6 +457,8 @@
                 global:
                     foo;
                     bar;
+                    woodly;
+                    doodly;
             };
             VERSION_2 {
                 global: