versioner: fix off-by-one error in header guard calculation.
This was causing redundant guards to be emitted in cases where
declarations were already guarded by another macro.
Bug: http://b/30170081
Change-Id: I9080838fbea5a56225df4b26d0918657fb6c4f21
Test: python run_tests.py
diff --git a/tools/versioner/tests/preprocessor_idempotence/expected/foo.h b/tools/versioner/tests/preprocessor_idempotence/expected/foo.h
new file mode 100644
index 0000000..ed31e8b
--- /dev/null
+++ b/tools/versioner/tests/preprocessor_idempotence/expected/foo.h
@@ -0,0 +1,12 @@
+#if __ANDROID_API__ >= 10
+int foo() __INTRODUCED_IN(10);
+#endif
+
+#if __ANDROID_API__ >= 21
+int bar(int) __INTRODUCED_IN(21);
+#endif
+
+#if __ANDROID_API__ >= 10
+int multiple_1() __INTRODUCED_IN(10);
+int multiple_2() __INTRODUCED_IN(10);
+#endif
diff --git a/tools/versioner/tests/preprocessor_idempotence/headers/foo.h b/tools/versioner/tests/preprocessor_idempotence/headers/foo.h
new file mode 100644
index 0000000..ed31e8b
--- /dev/null
+++ b/tools/versioner/tests/preprocessor_idempotence/headers/foo.h
@@ -0,0 +1,12 @@
+#if __ANDROID_API__ >= 10
+int foo() __INTRODUCED_IN(10);
+#endif
+
+#if __ANDROID_API__ >= 21
+int bar(int) __INTRODUCED_IN(21);
+#endif
+
+#if __ANDROID_API__ >= 10
+int multiple_1() __INTRODUCED_IN(10);
+int multiple_2() __INTRODUCED_IN(10);
+#endif
diff --git a/tools/versioner/tests/preprocessor_idempotence/run.sh b/tools/versioner/tests/preprocessor_idempotence/run.sh
new file mode 100644
index 0000000..1b0aae2
--- /dev/null
+++ b/tools/versioner/tests/preprocessor_idempotence/run.sh
@@ -0,0 +1,4 @@
+rm -rf out
+set -e
+versioner headers -i -o out
+diff -q -w -B out expected