fast triangulate single “sub paths”

We were triangulating single paths using a simple and fast triangulator, but most of our paths in Rive are container paths (shapes) with a single path inside of them. In that case we were always going through the slower triangulator (which does evenOdd/nonZero winding). This catches containers with a single path and lets them go through the fast path too.

Diffs=
ed84a5ca3 fast triangulate single “sub paths”

.rive_head

diff --git a/.rive_head b/.rive_head
index 3bc8648..4a69d7f 100644
--- a/.rive_head
+++ b/.rive_head
@@ -1 +1 @@
-4bc43ad929a73747f0ed51401d0b9a2d69188bb9
+ed84a5ca3153d142172d258bda071a98de3dd0e7

tess/src/tess_render_path.cpp

diff --git a/tess/src/tess_render_path.cpp b/tess/src/tess_render_path.cpp
index 5fa23db..6599931 100644
--- a/tess/src/tess_render_path.cpp
+++ b/tess/src/tess_render_path.cpp
@@ -82,7 +82,7 @@
     // doing any funky self overlapping winding and we'll try to triangulate it
     // quickly as a single polygon.
     if (m_subPaths.size() == 0) {
-        if (!m_rawPath.empty()) {
+        if (!empty()) {
             Mat2D identity;
             contour(identity);
 
@@ -94,7 +94,26 @@
 
             containerPath->addTriangles(contour, m_earcut.indices);
         }
+    } else if (m_subPaths.size() == 1) {
+        // We're a container but we only have 1 path, let's see if we can use
+        // our fast triangulator.
+        SubPath& subPath = m_subPaths.front();
+        auto subRenderPath = static_cast<TessRenderPath*>(subPath.path());
+        if (subRenderPath->isContainer()) {
+            // Nope, subpath is also a container, keep going.
+            subRenderPath->triangulate(containerPath);
+        } else if (!subRenderPath->empty()) {
+            // Yes, it's a single path with commands, triangulate it.
+            subRenderPath->contour(subPath.transform());
+            const SegmentedContour& segmentedContour = subRenderPath->segmentedContour();
+            auto contour = segmentedContour.contourPoints();
+            auto contours = Span(&contour, 1);
+            m_earcut(contours);
+
+            containerPath->addTriangles(contour, m_earcut.indices);
+        }
     } else {
+        // We're a container with multiple sub-paths.
         TESStesselator* tess = nullptr;
         for (SubPath& subPath : m_subPaths) {
             auto subRenderPath = static_cast<TessRenderPath*>(subPath.path());