Update Flutter licenses golden file (#4606)

vulcan_provider.{cc.h} were added in
fb9782a5. This updates the licenses
golden file to include them and fix the current breakage on Travis.

travis/licenses_golden/licenses_flutter

@@ -1223,6 +1223,8 @@ FILE: ../../../flutter/third_party/txt/src/txt/platform_mac.mm
 FILE: ../../../flutter/vulkan/skia_vulkan_header.h
 FILE: ../../../flutter/vulkan/vulkan_native_surface_magma.cc
 FILE: ../../../flutter/vulkan/vulkan_native_surface_magma.h
+FILE: ../../../flutter/vulkan/vulkan_provider.cc
+FILE: ../../../flutter/vulkan/vulkan_provider.h
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