Fix broken compilation of regal tests (#21248)

This should have been part of #21096.  These failures don't show up in
CI because they are disabled under swiftshader.

Author: sbc100

test/test_browser.py

@@ -2080,7 +2080,7 @@ def test_cubegeom_pre(self):
   @requires_graphics_hardware
   @no_swiftshader
   def test_cubegeom_pre_regal(self):
-    self.btest('third_party/cubegeom/cubegeom_pre.c', reference='third_party/cubegeom/cubegeom_pre.png', args=['-sUSE_REGAL', '-DUSE_REGAL', '-lGL', '-lSDL'])
+    self.btest('third_party/cubegeom/cubegeom_pre.c', reference='third_party/cubegeom/cubegeom_pre.png', args=['-sUSE_REGAL', '-DUSE_REGAL', '-lGL', '-lSDL', '-lc++', '-lc++abi'])
 
   @requires_graphics_hardware
   @no_swiftshader
@@ -2199,7 +2199,7 @@ def test_cubegeom_pre_vao(self):
   @requires_graphics_hardware
   @no_swiftshader
   def test_cubegeom_pre_vao_regal(self):
-    self.btest('third_party/cubegeom/cubegeom_pre_vao.c', reference='third_party/cubegeom/cubegeom_pre_vao.png', args=['-sUSE_REGAL', '-DUSE_REGAL', '-lGL', '-lSDL'])
+    self.btest('third_party/cubegeom/cubegeom_pre_vao.c', reference='third_party/cubegeom/cubegeom_pre_vao.png', args=['-sUSE_REGAL', '-DUSE_REGAL', '-lGL', '-lSDL', '-lc++', '-lc++abi'])
 
   @requires_graphics_hardware
   @no_swiftshader