Disable SkJumper assembly in cross builds for now.

Bug: chromium:762167
Change-Id: Ia23f6dbfc0466aef4ca9d1a5b9ff343d79dc83bb
Reviewed-on: https://skia-review.googlesource.com/47460
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>
diff --git a/gn/core.gni b/gn/core.gni
index 748e44a..eb0d0d2 100644
--- a/gn/core.gni
+++ b/gn/core.gni
@@ -521,8 +521,15 @@
   "$_src/jumper/SkJumper_stages.cpp",
   "$_src/jumper/SkJumper_stages_lowp.cpp",
 ]
+skia_core_defines = []
 if (is_win) {
-  skia_core_sources += [ "$_src/jumper/SkJumper_generated_win.S" ]
+  if (host_os == "win") {
+    skia_core_sources += [ "$_src/jumper/SkJumper_generated_win.S" ]
+  } else {
+    # TODO(thakis): Enable jumper in linux->win cross builds once the
+    # assembler situation is figured out, https://crbug.com/762167
+    skia_core_defines += [ "SK_JUMPER_USE_ASSEMBLY=0" ]
+  }
 } else {
   skia_core_sources += [ "$_src/jumper/SkJumper_generated.S" ]
 }