harden and speed up path op unit tests

PathOps tests internal routines direcctly. Check to make sure that
test points, lines, quads, curves, triangles, and bounds read from
arrays are valid (i.e., don't contain NaN) before calling the
test function.

Repurpose the test flags.
- make 'v' verbose test region output against path output
- make 'z' single threaded (before it made it multithreaded)

The latter change speeds up tests run by the buildbot by 2x to 3x.

BUG=

Review URL: https://codereview.chromium.org/19374003

git-svn-id: http://skia.googlecode.com/svn/trunk@10107 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/PathOpsExtendedTest.h b/tests/PathOpsExtendedTest.h
index 723135a..303d10c 100644
--- a/tests/PathOpsExtendedTest.h
+++ b/tests/PathOpsExtendedTest.h
@@ -28,6 +28,8 @@
 extern void showOp(const SkPathOp op);
 extern bool testPathOp(skiatest::Reporter* reporter, const SkPath& a, const SkPath& b,
                         const SkPathOp , const char* testName = NULL);
+extern bool testThreadedPathOp(skiatest::Reporter* reporter, const SkPath& a, const SkPath& b,
+                        const SkPathOp , const char* testName = NULL);
 extern bool testSimplify(SkPath& path, bool useXor, SkPath& out, PathOpsThreadState& state,
                          const char* pathStr);
 extern bool testSimplify(skiatest::Reporter* reporter, const SkPath& path);