Add config options to run different GPU APIs to dm and nanobench

src/gpu/gl/mesa/SkMesaGLContext.h

Index: src/gpu/gl/mesa/SkMesaGLContext.h
diff --git a/src/gpu/gl/mesa/SkMesaGLContext.h b/src/gpu/gl/mesa/SkMesaGLContext.h
index a58f1c890ee92cf05834f9f851524ef9e86da354..a9c77a81da41d0149e3f0d94a9952c18022da5fc 100644
--- a/src/gpu/gl/mesa/SkMesaGLContext.h
+++ b/src/gpu/gl/mesa/SkMesaGLContext.h
@@ -19,10 +19,7 @@ private:
 public:
     ~SkMesaGLContext() override;
 
-    static SkMesaGLContext* Create(GrGLStandard forcedGpuAPI) {
-        if (kGLES_GrGLStandard == forcedGpuAPI) {
-            return nullptr;
-        }
+    static SkMesaGLContext* Create() {
         SkMesaGLContext* ctx = new SkMesaGLContext;
         if (!ctx->isValid()) {
             delete ctx;