versioner: refactor to use CompilerInstance directly.

This will make it easier to switch over to a virtual filesystem,
which should drastically improve performance.

This also fixes an issue with warning/error reporting.

Bug: http://b/32748936
Test: python run_tests.py
Change-Id: I2e967acf75db29c95f3a03f4f94cccd22c367ad5
diff --git a/tools/versioner/tests/compilation_error/run.sh b/tools/versioner/tests/compilation_error/run.sh
index a34fda8..7e8d489 100644
--- a/tools/versioner/tests/compilation_error/run.sh
+++ b/tools/versioner/tests/compilation_error/run.sh
@@ -1 +1 @@
-versioner headers -p platforms -r arm -a 9 -i
\ No newline at end of file
+versioner headers -p platforms -r arm -a 9 -i -j1