Rewrite std::string("") to std::string(), Linux edition.

courgette/bsdiff_memory_unittest.cc

Index: courgette/bsdiff_memory_unittest.cc
diff --git a/courgette/bsdiff_memory_unittest.cc b/courgette/bsdiff_memory_unittest.cc
index f1718e2aa9e7be5b019c9011e426df0d25ed3c8b..fe9fae6ed02f31a158c346485123091e11909933 100644
--- a/courgette/bsdiff_memory_unittest.cc
+++ b/courgette/bsdiff_memory_unittest.cc
@@ -51,15 +51,15 @@ std::string BSDiffMemoryTest::GenerateSyntheticInput(size_t length, int seed)
 }
 
 TEST_F(BSDiffMemoryTest, TestEmpty) {
-  GenerateAndTestPatch("", "");
+  GenerateAndTestPatch(std::string(), std::string());
 }
 
 TEST_F(BSDiffMemoryTest, TestEmptyVsNonempty) {
-  GenerateAndTestPatch("", "xxx");
+  GenerateAndTestPatch(std::string(), "xxx");
 }
 
 TEST_F(BSDiffMemoryTest, TestNonemptyVsEmpty) {
-  GenerateAndTestPatch("xxx", "");
+  GenerateAndTestPatch("xxx", std::string());
 }
 
 TEST_F(BSDiffMemoryTest, TestSmallInputsWithSmallChanges) {