Rename test.

Author: brendandahl

test/embind/test_bigint.cpp test/embind/test_embind_bigint.cpptest/embind/test_bigint.cpp renamed to test/embind/test_embind_bigint.cpp

@@ -3301,7 +3301,7 @@ def test_embind_return_value_policy(self):
     'asyncify': [['-sASYNCIFY=1']]
   })
   def test_embind_bigint(self, args):
-    self.do_runf('embind/test_bigint.cpp', '1000000000000n\n-1000000000000n',
+    self.do_runf('embind/test_embind_bigint.cpp', '1000000000000n\n-1000000000000n',
                  emcc_args=['-lembind', '-sWASM_BIGINT'] + args)
 
   @requires_jspi